Comparative, Lightweight
Written by: Charles Lindsey, 6/22/02 (updated: 6/26/02) |
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This review began with the initial intent of comparing two sets of three bags which appeared to be direct competitors, based solely on specifications. The bags included three which are rated 25 to 30 degrees (Western Mountaineering Ultralite, Marmot Hydrogen and the new Mountainsmith Wisp) and three which are rated 15 to 20 degrees (Western Mountaineering Versalite, Marmot Helium and the new Mountainsmith Vision). That was the original mission statement.
As word spread about the bag review, the list of bags to be reviewed grew beyond the original six, to include bags by Big Agnes, Exped, Nunatak and Moonstone. Whereas the head to head comparisons for the original six bags are pretty straightforward, the additions of the other bags created a bag potpourri wherein comparisons became more difficult. Nevertheless, I think you'll find ample comparative information provided here to assist you in researching bags for your own use. After all, that's the bottom line and the sole underlying reason for the review.
A short word about procedure. I considered two approaches for the review. My first choice was to assemble a team of gear connoisseurs to venture into the Cascades for six days, each taking a turn with each bag. The team would also develop and use a common rating system rendering common data for ultimate rankings. Again, with the bags arriving slowly and the number of bags increasing, it became problematic to set a definite schedule wherein a team could be formed and trip plans prepared.
So, in order to get on with it and to take advantage of the late winter, early spring cold temperatures, I took a different approach. I decided to conduct the review myself with available and similarly experienced family members. I didn't have time to develop a numerical rating system, so decided to collect common data and weigh it relatively, according to the following:
30% -- Bag design/features/details/functionality (design features and details with a view to making the bag lighter weight as well as functional get better scores than design features and details which add functionality by making the bag heavier)
30% -- Subjective experiences - such as, how does it feel, was I comfortable, did I experience any cold spots, do I just love the bag, etc.
In any case, a good comparative review requires the same persons doing all the analysis in order to arrive at consistent, comparable information. That, I believe, we have accomplished.
Since there were different kinds of bags reviewed, direct comparisons were not so straightforward. For example, the Big Agnes Zirkel and Horse Thief have no insulating down on the bottom of the bag.
In a way, comparing the BA bags with the other lightweight bags is like comparing apples and oranges. To say the Zirkel is a 20 degree bag while looking at the WM Versalite (20 degrees) and Marmot Helium (15 degrees) does not initially compute. Both the Versalite and Helium have almost twice the loft as the Zirkel. Yes, when a person lays on the insulation on the bottom of the Versalite or Helium it becomes of little value and reduces effective loft to the 4 inches on the top of the bag which is more comparable to the Zirkel. Tempting as it is, we should be careful making that kind of comparison because all the lightweight bags that we're looking at here (with exception of the BA bags and the Exped Hummingbird) have continuous baffles. We can easily shift most of the down in the WM and Marmot bags to the top of the bag and put a mattress underneath (in effect, similar to the Big Agnes bags). So, to help normalize the comparison of the Zirkel with the other two bags, we could shift most of the down in the Marmot Helium and WM Versalite to the top of each bag, add the 1 1/2 inch mattress resulting in roughly 7 to 7 1/2 inches of "loft". The Zirkel is about 4 1/2 inches including the mattress.
Another consideration is that manufacturers' ratings are not standardized nor consistent. The Versalite is more like a 10 degree bag, for example, rather than a 20 degree bag.
Furthermore, loft alone is not an accurate measure of a bag's potential insulating capability. The Zirkel, in addition to its loft, also has excellent features which add to its temperature rating, such as passive collar, snugly-fitting hood, generously-filled and effective zipper draft tube as well as additional draft tubes around the circumference of the integrated mattress pad. Another variable to factor-in is that the mattress inserted into the Zirkel's integrated mattress sleeve provides a stabilized bottom insulator which remains in place even when a person tosses and turns in the bag. Whereas, with the other two bags, the mattress is not a stable source of insulation. This being a particular problem when down is shifted from the bottom to the top of the bag. Subsequently, when a person rolls over it often exposes the bag's downless bottom which has moved away from the no-longer-insulating mattress and a cold rump is the result.
Stop! Hold it, you say. Why all the above gibberish?
In making comparisons, several of the things we consider are that (1) manufacturer's specs are not standardized and are often misleading and incomparable (2) loft isn't everything (3) good design adds to temp rating, thus (4) additional discussion and details are needed to present a holistic view of each bag, in order to make comparisons more meaningful - which we attempt to do throughout this review.
A note regarding stuff sack size. Since we do not consider it a healthy practice, we did not try to see how small we could stuff each bag. Most of the bags fit comfortably in a 7 x 7 x 14 inch sil-nylon stuff sack, several in a 7 x 7 x 10. Point is, we didn't scrutinize this point. One highlight, here, is that the Exped Hummingbird had its one moment in the spotlight. Whereas we need to add 22 grams for the stuff sack to each of the other bag's total weight, the Hummingbird has its own integrated stuff sack (which may itself weigh 22 grams) (view it here).
I tested each bag, in the field (literally) with no shelter (tent, tarp or otherwise), no ground cover (other than a 1 1/2 inch mattress), and wore no clothes (other than a pair of hiking shorts). I have never categorized myself as a warm or cold sleeper, as they say, so I can't offer that bit of help. The "TLB" rating that I assigned is an indicator that expresses to what temperature I would be comfortable, in the bag, under these test conditions. I took a conservative approach and basically either agreed or disagreed with the manufacturer's specs. I didn't try to nail down an exact temp rating beyond that. Although, in the case of the Western Mountaineering bags, the specs were obviously understated so I made mention of that fact. Surprisingly, most of the bags were true to their temp rating in these conditions, although a few appeared to be overstated. In a tent, wearing clothes, a person should be able to milk another 5 to 10 degrees out of a bag. For example, in a tent, probably wearing clothes, I would be confident using the 25 degree WM Ultralite at 15 degrees.
DISCLAIMER:
Keep in mind, I attempt to provide, here, some guidance based upon my experiences and observations. Although I'm confident in the information that I publish, I will accept no responsibility for your application of the information. If you strictly follow the information contained herein and subsequently, it doesn't work out for you, I will genuinely empathize with you, but I will accept no responsibility for your decisions. I strongly suggest that you do your own empirical analyses while using this review as one of your resources. As they say, "hike your own hike" or "research your own gear".
A comparative chart accompanies this page as an important part of the overall review. The components of the chart are as follows:
GENERAL DISCUSSION:
All eleven bags in this review use quality, high-tech materials (shell, liner, hardware & insulation). All have quality construction (straight seams, tight stitching, minimal dangling threads, and an overall balanced appearance), and all have quality "waterproofing". Across the board the quality of materials and construction are very good.
It has become apparent to me that while there are some observational differences in the quality of materials and construction, for the most part the differences between bags lie largely in the details and functionality of the bag designs.
So, our quality focus will not be on materials and construction, but rather on design features, details and functionality.
For example, for zipper snag prevention, the robust tape stiffener along the zipper track of the Marmot and Western Mountaineering bags speak quality. You know they will work great even before crawling into the bag. Again, using Marmot and Western Mountaineering as examples, their hoods don't necessarily have any more or better insulation and materials, but the reverse differential design on the WM bags and the added circular face muff on the Marmot bags makes their hoods a zillion times more comfortable and functional.
I took one look at the Big Agnes Zirkel and thought to myself, man, whoever designed this bag has a great deal of experience and vision. It has a wonderful, apparently articulated hood. When you tighten it, the down is not at all compressed. It has down-filled draft tubes surrounding the mattress sleeve. The mattress sleeve! The horse-collar shaped passive collar that hangs down and neatly and snuggly surrounds the neck, and the integrated pillow sleeve. My, what ingenuity. Sure, all those features add weight, but the creative features and overall functionality and quality of the BA bags is impressive.
The Nunatak Alpinist is another example of a bag maker taking a risk to produce a leading-edge product - lighter bag with lower temp rating. The Alpinist was the only bag in the review that did not have a zipper opening. Thus, without the requirements for hardware and draft tubes, the Alpinist was one of the lightest bags in the review. Also, very comfortable. I would say certainly one of the most comfortable bag lining materials in the review. Extremely comfortable to slide into the bag and be engulfed by the silky smooth yet substantial Pertex rip-stop nylon. Of course, the reason that the material draps around and engulfs one's body is also the source of the major problem for this bag, which we will discuss in length in the individual bags section.
Last but not least, we need to mention the thoughtful design features of the Moonstone 800 Lucid. The Lucid features an anatomically shaped hood with generously filled down tubes that run parallel to the body; ground-level side seams; trapezoid-shaped baffles; and anatomic-shaped footbox.
All bags (with exception of Western Mountaineering bags, Exped Hummingbird and Nunatak Alpinist) feature a single, wrap-around zipper which not only functions as both inside and outside zipper, but also is easily moved away from the face when the hood is drawn shut. A very practical, thoughtful implementation.
QUALITY, ATTENTION TO DETAIL & INNOVATION BEYOND PAPER-THIN MATERIALS: (Marmot, Western Mountaineering, Moonstone and Big Agnes bags lead the way)
ZIPPER TRACK STIFFENER TAPE / BACKED BY DOWN-FILLED DRAFT TUBE: (Western Mountaineering bags are tops, Marmot bags are very close second)
One of the problems with meting out ratings is that we tend to lose sight of the fact that all these bags are high-end products and each one may, in fact, be the most preferred product in certain situations or environments. All the bags use high-tech materials, employ innovative designs, are well made, are lightweight (or they wouldn't be here) and are relatively expensive (which may not be a good indication of quality or usefulness but might be). The following discussion delves into the relative usefulness of several bags which might otherwise be overlooked.
LIGHTEST, FULL-ZIP, NON-SEWN-THRU, DOWN BAG ?
Are you looking for the lightest, full-zip, baffled, 700-fill down sleeping bag on the market? The Exped Hummingbird may be that bag. Since its zipper extends to the bottom of the bag, and it has side blocked baffles, it can easily be used as a quilt for one or two persons. However, as cautioned elsewhere in this review, the small amount of down in this bag requires frequent and careful down redistribution to avoid cold spots (also known as "see-thru-spots").
MUMMIES FOR BIG PEOPLE:
Interested in lightweight gear but not too fond of narrow profile mummy bags? The Big Agnes bags have ample room for moving around and are well suited for folks who don't like or just flat out don't fit a standard mummy bag. The Horse Thief and Zirkel have a generous 67.5" shoulder area and 64" hip section. The Mountainsmith Vision and Wisp aren't too far behind with their 64" shoulder and 58" hip girth.
BAGS FOR HAMMOCK USERS:
Tired of your mattress popping out from under you when you're trying to dose off in your hammock or simply tossing and turning? The Big Agnes Zirkel and Horse Thief have a mattress sleeve on the bottom of the bag instead of insulation. This feature is attractive for hammock users (especially if you use the Big Agnes Air Core Mummy Mattress with lengthwise tubing which is flexible and may shape itself to the hammock better than stiffer mattresses). For hammock use, the mattress in the sleeve provides both stability (since you can't slip off your mattress and the stiffness of the mattress keeps the bag in place when you toss and turn) as well as bottom-side insulation from the cold.
A BAG FOR SHORTER FOLKS ?
Apparently lost in the competition between the Marmot, Western Mountaineering and Mountainsmith bags, the Moonstone 800 Lucid is a very solid bag with innovative features not seen on most of the other bags. The Lucid is an excellent option for folks who do not tolerate wasted space or utility. The regular-size Lucid is a shorter bag intended for the 5'9" person of medium build (absolutely no taller than 5'10"). The Nunatak Alpinist and Big Agnes Zirkel and Horse Thief are also designed for folks up to 5'10". Also, as a side note, Western Mountaineering offers some of their bags, like the Apache, in a 5-foot 6-inch size.
WHAT ABOUT COLD FEET ?
The Moonstone Lucid has a very innovative footbox design, with extra insulation, as described in the "Quality - Innovation" and "Individual Bags" sections of this review. The Marmot Helium & Hydrogen also both have the same 40-inch, trapezoidal-shaped footbox design as does the Lucid - very roomy, natural and comfortable. No more toes poking into the insulation and getting cold (at least for me with 9.5 foot size).
ZIPPER LENGTH IS IMPORTANT:
Change is often good, but it sometimes doesn't come quickly for me. My concept is that a full-zip bag is a must. It is the most functional and most practical (and most heavy). With a full-zip bag you can easily unzip it all the way and use it as a quilt for one or two people or to zip-in a bag extender like the Sweetie Pie to create a two-person sleeping bag. Not to mention (but I will) the critical function of airing out the feet, especially during hot weather. Yessir, the full-length zip is the ONLY way to go - or is it?
Consider this - if you don't need to use your bag as a quilt or zip together with another bag to make a two-person bag, you can save weight by getting a 3/4 zip or 1/2 zip bag. With these bags, you still have some ventilating capability. In the Marmot Helium and Hydrogen, I am able to lift my knees up and hang a leg out to cool off or if over-heated, open up the bag to the half-way point and use the bag as a quilt to the extent possible. It works for me. It's easier with the 3/4-zip bags, of course, but also possible with the 1/2 length zip bags.
If you're in the cold and don't anticipate overheating or needing to ventilate, the no-zip Nunatak Alpinist may be a good choice for a go-fast, lightweight bag. Also, in the colder weather the 1/2 and 3/4 length colder-rated bags like the Marmot Helium and Moonstone Vision do very well.
TOSS AND TURN ALOT ?
Several thoughts here. If you toss and turn alot during the night, you might want to consider either a bag which has generously-stuffed down tubes, with good down control ("sticky", flexible, baffle material necessary) such that your thrashing about will not significantly shift and reposition the down insulation causing cold spots. Several bags come to mind -- Western Mountaineering Ultralite & Versalite, Marmot Helium & Hydrogen, Big Agnes Zirkel and Horse Thief and Mountainsmith Vision. You may also want to consider a bag with ample room with which to adjust your sleeping position in the bag without moving the bag itself. The Big Agnes Zirkel and Horse Thief are the most roomy bags followed by the Mountainsmith Vision and Wisp. The Big Agnes Zirkel and Horse Thief have the added feature of the integrated mattress sleeve. When you toss and turn in a Big Agnes bag, because of the secure, stiff nature of the mattress, the bag does not move nor contort as you toss and turn. The BA bags are great for tossing and turning !
Conversely, you do not want to get a bag like the Nunatak Alpinist which has no down control. At some point during the night, your bag may look something like this and you will most likely have cold spots. Same goes for the Exped Hummingbird. On both those bags I created cold spots in the leg area just by lifting a knee and in the chest area by brushing my hand against the inner bag wall. On the other hand, if you do not toss and turn but tend to lay stationary, the Nunatak Alpinist and the others mentioned may be a good choice for you.
Although none of these bags are intended to be weather proof, they all are afforded a generous application of Durable Water Repellent (DWR) treatment to protect the down insulation from getting wet and becoming dysfunctional. The following tests were performed to observe how each bag performed, in relation to the other bags. The goal was to (1) examine how each bag's shell material responded to persistently applied water and (2) examine how each bag responded to water persistently applied to its always vulnerable seams.
We first created a little crater in at least two places on each bag and filled with eight to ten ounces of water. We let the water remain for at least 1/2 hour. After removing the water, we visually checked for wetout of the shell material, dampness/wetness of the down and dampness/wetness on the inside of the bag. The second test was similar except the puddles of water were positioned directly over the seams.
All bags passed the first test with relatively similar results. All bags failed the second test, with relatively similar results.
TEST #1 RANKINGS (shell material):

A sweet 20 to 25 degree bag! When I first took the Ultralite out of its box, I had the impression of a sleeping-bag-shaped, down-filled balloon. It puffed up very quickly. Make no mistake, though, the Western bags, to include the Ultralite, are legitimate mummy bags with a narrow profile. To illustrate, the Ultralite has a 59" girth, the Marmot Hydrogen has a 62" girth, the Mountainsmith Wisp has a 64" girth and the Big Agnes Horse Thief has a 67.5" girth. The Ultralite is the most narrow by a good margin. While the narrow profile is the most efficient at retaining and making body heat useful, it also restricts movement within the bag. I'm 5 foot 9 inches tall and 170 pounds and have "adequate" room to move. I've learned how to toss and turn, if I must, inside the bag without moving the bag. This allows me to shift a majority of the down to the top of the bag, when needed, for extra insulating power without worrying about getting a cold rump.
It has Western's reverse differential hood with the inside fabric of the hood cut larger than the outside so the hood lofts around your face at night and you can lay out in the open and stay nice and warm without having to pull the drawstring down to a tiny opening for breathing.
Western uses a #5 YKK coil zipper with two dual direction zippers, each with double pull tabs (one inside/one outside) and locking head. The coil construction has a less abrasive surface in the event of zipper snags which is unlikely to happen on this bag. Of all the bags, the WM bags have the best zipper-snag-preventing, fabric-stiffening tape along each side of their zipper track.
With its full-zip, dual zippers and continuous baffles, it functions well as a summer bag or quilt. With its excellent hood, robust zipper draft tube and generously stuffed down tubes, it also does the job in cooler spring and fall temps, well below freezing. Of course, quality of materials and construction and overall comfort are also superior. It's a lot of bag with a lot of functionality for 1 lb, 11.584 oz (782 grams).
Improvements: Improve hood with more robust overfilled top down tube or add face muff to keep the drawcord toggle off the face.

A great 30 degree bag with ample room for a fully clothed me (at 5 foot 9 inches tall and 170 pounds) which makes it useful at even lower temperatures.
The Hydrogen is cut a little wider than the WM Ultralite, so if you might feel constricted in the Ultralite's narrow confines, I suggest trying this bag as your next option.
The Hydrogen's shell and liner are crafted from relatively durable 1.2 oz./sq. yard ParaLight DWR 30 denier yarns used with abrasion and tear resistance in mind. The feel of the fabric suggests that it, along with the fabric used on the Big Agnes bags, is the most durable of the bags in this review. The Hydrogen has an excellent DWR application. Marmot uses stretch tricot baffles which provides strength, durability and good down control. Marmot's velcro-free face muff design is the best. The muff keeps the drawcord and zipper away from your face and provides a snug, comfortable fit of the hood as it is being tightened. I get a snug fit well in advance of the hood being closed all the way. The hood drawcord is positioned for easy access yet remains out of the way.
Zipper guards, second only to the Western Mountaineering bags, help repel biting zipper coils. Smaller and shorter zipper to minimize weight, 38" long. One hang loop on outside of foot box-- the bare minimum. Generously down-filled draft tube significantly minimizes cold leaks through the zipper. The baffles are continuous down to the middle of bag (at zipper's end) so that down may be shifted in response to the weather conditions. The baffles are side blocked below the end of zipper which keeps the down in the lower part of the bag evenly distributed. Classic trapezoidal foot box for more foot room.
Improvements: none noted. On second thought, add 3 ounces of down and challenge the Ultralite as best all-around bag.

The Mountainsmith Wisp clearly will be a good choice for larger folks. The loft is less than the Marmot Hydrogen, but the Wisp accommodates a longer and wider person (it is probably comparable to the Western Mountaineering Megalite which didn't make it into this review). The Wisp is rated to 30 degrees but because the bag arrived late I did not have a chance to verify the temp rating. Based on what I've observed about the bag, in relation to the other bags that I have tested, I suggest it could be a 30 degree bag if you're a warm sleeper or if you're a cold sleeper with long underwear and maybe a lite fleece jacket. There's plenty of down fill in the hood and foot box, but the rest of the bag seems a little thin for the typical 30 degree bag.
When I slept in the Wisp, I more than once heard myself mutter something like "man this bag has a lot of room". I couldn't feel the end of the bag with my stretched out toes (I'm 5'9" when exercising good posture). I had to check the specs that came with the bag to make sure it wasn't a size Long. I was puzzled why the Wisp, having one more ounce of down, has 1/2 inch less loft throughout than does the Marmot Hydrogen. The reason - the Wisp is both longer and wider, but not by much. The Wisp also has a larger hood which requires some manuevering to get centered. By the way, night time temps dropped to only 45 degrees when I tried the Wisp, but I was toasty warm and comfortable.
The Wisp has an interesting feature wherein the draft tube extends around to become the top half of a neck draft collar. Don't see that on too many ultralight bags, although the Hydrogen also has a passive collar and the WM Ultralite to a lesser extent. Even though the Wisp has only a 1/2 zipper length, it has a double zipper, one on each end of the zipper track. This feature is unique to the Wisp (the Hydrogen has just one zipper) and provides additional ventilation capability. For their shell material, Mountainsmith uses Dimension Polyant Airnet fabric which is a 15 denier high-tenacity nylon with DWR treatment. I believe this is the same or similar material used on the Exped Hummingbird. It appears to be even lighter than the Western Mountaineering .85 oz per square yard material. Mountainsmith states that the material weighs .80 per square yard. For their liner material, they use a Pertex 30 denier nylon which is down proof, wind and water repellent.
I like the bag and at 1 pound, 6.08 ounces, it deserves serious consideration. Since the bag has ample room to accommodate a person fully clothed, with room to spare, this bag will take you below freezing temps.
Mountainsmith has put out a couple of lightweight contenders, but as you can see from the suggested improvements, below, they still need to improve these bags to bring them up to the current level of the Marmot and Western bags.
Improvements: Consider redistributing down such that a little more is added in the mid section. Beef-up the no-snag tape on the inside of the bag material or put it on the outside - either way make it wider than one inch. Use shorter & lighter cords & lighter cord pulls and toggles, add 1/2" more down loft in the hips to knees area & little less at feet and hood (or add one more ounce of down to the bag), reduce size of hood and transfer down saved to mid section of the bag. Add a face muff or differential cut to the hood (like the Marmot and Western Mountaineering hoods) so the hood lofts around the face without having to pull the drawstring down on top of your nose.
I like many things about this bag. It has superior water proofing (DWR application). Its silky bag lining and down content settle over the contour of one's body providing a very silky, comfortable and warm layer next to the skin. It is a simple design and since it doesn't have a zipper, there's no messing around with zipper anti-snag tape, draft tube, or zipper cover. With 11.5 ounces of 800-fill down and none required for draft tube, this bag has a lot of lofting power in a lightweight package.
Ahh, this could have been one of my favorite bags, but unfortunately, the 9 1/2" baffle width and wide vertical spacing (space between liner and shell) which allow for unrestricted down lofting, also allows for significant unrestricted down movement. Great care should be taken to periodically redistribute the down to ensure complete and adequate coverage or you may end up sleeping in a bag that looks like this.
When I first used the Alpinist, I very carefully distributed the down to give the bag even distribution of down with about 80% on top. By the time I worked my way into the zipperless bag, much of the down on top of the bag was gone and I had essentially two layers of nylon. I then redistributed the down from inside the bag, but shortly thereafter following a bit of arm movement, the down was again pushed away from the top of the bag in the chest area. I had the same problem with my knee movement easily shifting the down from the middle of the bag to the sides and letting the cold air in. First night I used it, I awoke chilly -- this at 40 degrees!!!
To complicate things a little, there is no zipper in this bag so the process of redistributing the down is not as straightforward as on bags which can be unzipped -- nevertheless it can be done.
The hood cord toggle is sewn to the bag which may cause an annoying and slow process of cinching/uncinching the hood - at least it did for me several times. I've seen a few bags that use this technique (e.g., the Moonstone 800 Lucid) and I've yet to do it well.
Taking all cautions into consideration, this is an excellent bag -- quality materials and construction.
Improvements: Consider making the baffle width 5 1/4" (approximately 1/2 of what it is currently), to provide stability for the down placement. Also, consider adding a down-filled face muff or reverse differential hood design to provide good seal of hood and to eliminate the hood closure cord and toggle from resting on the face when the hood is closed.

If you don't like the confinement of a hood and prefer to just wear a fleece cap, this could be the bag for you. The Horse Thief doesn't have a hood.
Just so the picture of the Horse Thief above doesn't deceive you, it has a 2 1/2" thick Big Agnes Air Core Mummy Mattress tucked neatly into its integrated mattress sleeve. Without the mattress the Horse Thief appears less lofty.
By the way, in testing the Horse Thief and the Zirkel, as well, I did not use the Air Core pad mentioned above, I used the Big Agnes-recommended REM 1 1/2 inch regular mummy pad. The pad is rated to zero degrees F. and weighs 34 ounces. For comparision purposes, the Air Core pad you see in the picture above weighs 22 ounces and is rated 32 degrees by Big Agnes.
This was my first experience in a no hood bag and I was surprised how enjoyable and comfortable it was to have my head less encumbered. Down to 30, it worked just fine. I wore my OR windstopper fleece hat. The Horse Thief's integrated pillow added insulation and comfort. The horse-shoe shaped passive neck collar nicely and comfortably sealed the bag opening against my neck and chin. I didn't take it lower than 30 but it was comfortable at that temp.
The main features of the Horse Thief:
The Horse Thief has ample room for moving around and is well suited for folks who don't fit a standard mummy bag. The Horse Thief has a generous 67.5" shoulder area and 64" hip section. It's filled with 11 ounces of 775-fill goose down, weighs approximately 1 pound, 12 ounces (size regular) and has a conservative rating of 35 degrees (I've been comfortable to 30 degrees, without tent, bivy or extra clothes).
As is the case with the BA Zirkel, the liner material used in the Horse Thief is comfortable. I get a feeling of spacious luxury when in these bags.
Improvements: None noted.

The above picture of the Zirkel shows the bag with the Big Agnes-recommended REM 1 1/2 inch regular mummy pad inserted into its integrated mattress sleeve. The pad is rated to zero degrees F. and weighs 34 ounces. It is the pad that I used while testing the Zirkel.
A lot of thought went into this bag. The details and features are unique and so far, no negatives, except the Zirkel is a relatively heavy bag. Even without insulation on the bottom half of the bag, it is the heaviest out of all eleven bags in this review. Most of the features which add functionality and comfort also add weight. I found the zipper to be a little testy when zipping up that last 12 inches or so (due to the unyielding stiffness of the sleeping pad). No big deal, just something to be aware of when in the bag. After the first few times of struggling a little, I discovered a good way to do it .
Here's the features list for the Zirkel:
It has a wonderful, apparently articulated hood. When you tighten it, the down is not at all compressed. As already described in detail elsewhere throughout this review, the Zirkel is a very luxurious bag.
Both of the BA bags have done well in most categories during this review. The main issue with these bags is that when used as designed with the Big Agnes mattresses, the sleep system becomes very heavy. For example, based on the weights below, the Zirkel plus the "lightest-weight" BA mattress, the Air Core Mummy, weighs a total of 3 pounds, 10.84 ounces (1668 grams). That's pretty heavy for a "lightweight" 20 degree bag. The Zirkel with the recommended REM 1 1/2" mummy sleep pad weighs 4 pounds, 6.62 ounces (2002 grams). By comparison, my personal sleep system, a WM Ultralite and Mt.Washington closed-cell pad weighs a total of 2 pounds, 2.53 ounces.
So, there's a tradeoff here. The features are wonderful. The weight is on the heavy side. Take your pick.
Improvements: Find innovative ways to reduce weight.

The Exped Hummingbird is the lightest bag in the review at 1 pound, 5.41 ounces. It is also the least warm bag. Although it has a manufacturer's rating of 30 degrees F. (comfort) and 23 degrees F. (extreme), I rate it no more than 40 degrees F. At its thickest, it has a maximum of 3 inches of loft. Since the side baffles are blocked (it has down tubes on each side running the length of the bag which effectively block off the sides), down cannot be moved from the bottom of the bag to fill in the sparse amount of down at the top and this is problematic. The bag really needs more down on top. Hold it up to the light at any time and see many potential cold spots where there isn't enough down, only two layers of nylon.
By the way, based on the bag's price tag and temperature rating, I was very surprised when I received it. Ironically, almost the same day that I received it, I was contacted by another gear reviewer independent of this review who was working on his own review of the bag. He also was surprised and wanted to know what my impressions were. As it turned out we both were in-sync in our observations. Based on our independent experiences with the Hummingbird, we both felt that the Hummingbird was, at best, a 40 degree bag and was comparable to the Western Mountaineering Highlite, a 40 degree bag, which we both had previously reviewed. I really like some of the materials, the weight and the overall potential of the Hummingbird. I'm hoping Exped will put some modifications into it in order to make it more competitive.
The Hummingbird has a double zip - which is problematic when the bag is zipped up and the hood cinched. You cannot move the zipper to the outside of the bag and it isn't covered by a face muff or anything. Thus, the zipper sits against your face. The outside zipper is not covered by the velcro closure which should cover the zipper, nor is the zipper on the inside covered by the draft tube to protect the face. The draft tube stops prematurely so that when the bag is zipped up the zipper will press into your face rather uncomfortably.
The Hummingbird's zipper cover is in a curious place. It doesn't cover the zipper and for some reason is 1 1/2 inches below the end of the zipper track. The Ideal is like on the Mountainsmith bags where the single wrap-around zipper wraps around to the outside and is covered by a small, velcro zipper cover, thus, the zipper is safely tucked away from getting in the way of the face or working itself loose.
Upside:
Downside:
Improvements: Exped has the beginnings of a good bag here. In its current state, recommend restating the temp rating to 40 degrees and dropping the price $100 to $199. For the future recommend:

The 800 Lucid is a solid bag that doesn't stand out like some of the bags but also doesn't have weaknesses that some bags have either. It's a solid all-around bag. As mentioned elsewhere in the review, the size regular is optimum for a person 5 foot, 9 inches tall (or shorter). Absolute maximum is 5 foot, 10 inches. The bag has a narrow shoulder girth of 59 inches (same as the WM Ultralite), but a very roomy foot box on the other end (see bag photo above).
One interesting note about the Lucid. The shell material is almost transparent and you can see the down clusters inside.
The Lucid includes many innovative details that add value to its overall performance. Those features are:
Variable Thickness
A thermographic image of your body would show you lose more warmth around your head, torso and feet, and less over your legs and arms. Consequently, the Lucid has more insulation around the head, more over the upper body, and more around the feet. The result is a thermally efficient bag.
Anatomically shaped hoods
Anatomically shaped hoods reduce compression of insulation when drawcords are pulled tightly. Plump vertical down tube sections in the hood positioned such that one's head is more uniformly and efficiently surrounded by the down insulation. This design also prevents the down from being compressed as the hood is drawn closed, allowing the insulation to maintain its loft when these cords are tightened.
Differential Cut
Moonstone bags are 3-dimensionally shaped to follow the form of your body. The outer shell is cut larger than the liner. The inside measurements are standardized for all bags, whereas the shell circumference and outside length increase with the amount of insulation put in the bag. This allows the insulation to retain its full loft and reduces compression through movement.
Anatomic Footbox
The anatomic footbox follows the natural movement of your feet. It is wider at the toes and narrower at the heels. The new anatomic shape eliminates dead air space and keeps your feet warmer.
Ground Level Side Seams
The Lucid utilizes Ground Level Side Seams to minimize exposure and prevent heat loss from the bottom of the bag, which is less insulated. The full-length dual zippers are placed at ground level to protect against heat loss.
Moonstone Trapezoid Baffles
Trapezoid baffles are the lightest solution. They oppose one another to keep chamber volume constant and down securely in place.
Smart Draft Tubes
Moonstone’s single draft tube hangs from the top and provides an effective seal as gravity works with the tube. The draft tubes are oversized and off-set, so they press against the zipper at all times. Anti-snag tape keeps the fabric from catching in the zipper.
Pertex® X-Ray 1.1
Moonstone's X-Ray shell material is built from a 30Denier high tenacity parachute yarn.
Improvements: Add face muff or similar functionality to keep hood draw cord and draw cord toggle off of face and provide an effective seal for keeping in warm air and keeping out cold air. Add small zipper cover flap to help secure zipper away from face.

What do you think ? Six to Seven inches of loft; bulging, down-filled draft tube; awesome, snug hood; plump, passive down collar. Does this sound like the description of a 20 degree bag ? The Marmot Helium is rated 15 degrees and I agree. The Versalite, which has more loft and similar features, is rated 20 degrees and I disagree. It also should be rated, conservatively, at 15 degrees. In fact, I believe if you find yourself in temps of 10 degrees and you have the Versalite in your pack, you'll sleep as snug as a bug in a rug!!
The Versalite features the Western Mountaineering reverse differential hood with the inside fabric of the hood cut larger than the outside so the hood lofts around your face at night and you can lay out in the open and stay nice and warm without having to pull the drawstring down to a tiny opening for breathing.
A solid down-filled, passive top collar protects you from the cold. 62" of shoulder girth is roomy enough to accommodate long underwear and fleece outer layers, and the total weight is only 2 lbs. 4 oz.
Western uses a #5 YKK coil zipper with two dual direction zippers, each with double pull tabs (one inside/one outside) and locking head. The coil construction has a less abrasive surface in the event of zipper snags which is unlikely to happen on this bag. Of all the bags, the WM bags have the best zipper-snag-preventing, fabric-stiffening tape along each side of their zipper track.
I love this bag. If I didn't save 1/5 pound by taking the Helium, I've just as soon take the Versalite - it's a toss up. The thing about the Versalite is that I have the sense that I'm buried in down, especially when I cinch down the hood. Man, what a comfortable and well-sealing hood - with cords, cord locks and zippers well off my face. This is a serious bag and well-suited for cold weather in the teens. It also has the full zip with two, double zippers so that you can unzip the bottom for ventilation or to use as a quilt.
Improvements: None noted.

A true 15 degree, 2 pound bag. Marmot did not leave out functionality to achieve the weight savings. They clearly put considerable thought into the details and the result is a simple, functional, comfortable ultralight bag. The Helium has features which rival much heavier three season bags, and does so without sacrificing durability.
My first thoughts as I slid into the Helium were of comfort, durability and all-together usefulness and compactness. No excess nor lack. A very comfortable night's sleep.
The Helium's shell and liner are crafted from relatively durable 1.2 oz./sq. yard ParaLight DWR 30 denier yarns used with abrasion and tear resistance in mind. The feel of the fabric suggests that it, along with the fabric used on the Big Agnes bags, is the most durable of the bags in this review. The Helium has an excellent DWR application. Marmot uses stretch tricot baffles which provides strength, durability and good down control. Marmot's velcro-free face muff design is the best. The muff keeps the drawcord and zipper away from your face and provides a snug, comfortable fit of the hood as it is being tightened. I get a snug fit well in advance of the hood being closed all the way. The hood drawcord is positioned for easy access yet remains out of the way.
Zipper guards, second only to the Western Mountaineering bags, help repel biting zipper coils. Smaller and shorter zipper to minimize weight, 38" long. One hang loop on outside of foot box-- the bare minimum. Generously down-filled draft tube significantly minimizes cold leaks through the zipper. The baffles are continuous down to the middle of bag (at zipper's end) so that down may be shifted in response to the weather conditions. The baffles are side blocked below the end of zipper which keeps the down in the lower part of the bag evenly distributed. Classic trapezoidal foot box for more foot room.
This is a solid bag!
Improvements: None noted.

The Vision is a beefy bag, with 21 ounces of 750-fill down. Surprisingly, this large, plump bag which easily accommodates a 6 foot tall person and has a 64 inch shoulder girth, weighs less than two pounds. Pretty impressive.
For their first venture into bag making, MS did a pretty good job. As might be expected, they have several opportunities for improvements. My first impression, after crawling into the Vision was that the hood was overly large, but after repositioning myself I found a "sweet" spot wherein the blow hole formed by cinching the hood closed was comfortably centered above my mouth and nose.
No anti-snap stiffener visible, however, it is hard to tell but upon very close scrutiny, there appears to be some kind of stiffener tape on the inside of the bag extending out approximately one inch from each side of the zipper track. On the visible, exterior side no tape is visible, but MS uses extra stitching to reinforce the area approximately one inch on either side of the zipper track. They add four rows of stitching 1/4 inch apart -- totaling one inch in width. This technique is functional but not as effective as that on the Marmot, WM or Moonstone bags. I did experience some snagging, primarily due to the reinforced area not being wide enough -- one inch isn't enough.
Zipper track is backed by a medium-sized draft tube which extends around to form the top half of the neck collar. The Vision, unlike the Marmot Helium and Western Versalite, has a full down-filled neck collar (top and bottom) which undoubtedly adds to its heat retention capability.
I do find it peculiar that Mountainsmith would go to great lengths to produce these ultralight bags and then put on the same cords, bungee cords, cord locks and cord lock pull tabs that they use on their backpacks. They probably could have found a better solution. Their bags are very similar to the Marmots bags in their details, so I'm surprised they didn't pick up on using a simple lightweight cord, period, like Marmot does. Anyway, that's just an opportunity for you and me to shave the bag weight and for Mountainsmith to make improvements.
The .80 oz per sq yard shell material is very much like that of the .85 oz Western Mountaineering Extremelite shell material. As is true with almost all the bags in this review, each of the Mountainsmith bags comes with a (sil-nylon) stuff sack and a (cotton) storage sack.
The loft in the hip/leg area of the Vision is slightly less than the Marmot Helium but slightly more than the Helium in the foot area. The Vision will be a good choice for larger folks. It can more easily accommodate a longer and wider person or a person who chooses to wear their clothes to bed.
Improvements: Beef-up the no-snag tape on the inside of the bag material or put it on the outside - either way make it wider than one inch; use shorter & lighter cords & lighter cord pulls and toggles; add 1/2" more down loft in the hips to knees area & little less at feet and hood; reduce size of hood and transfer down saved to mid section of the bag. Add a face muff or differential cut to the hood (like the Marmot and Western Mountaineering hoods) so the hood lofts around the face without having to pull the drawstring down on top of your nose.
BEST BAG (quality, design, comfort, weight):
BEST BAG (all-around functionality):
SUMMER / THREE-SEASON (20-40):
The WM Ultralite is 3.75 ounces heavier than the Marmot Hydrogen but also has 4 ounces more insulation. Both bags are excellent but the Ultralite wins first place due to its broader range of utility over a full three seasons. This was a difficult decision as I'll explain with further discussion. Although the Hydrogen has less down/loft/insulating capacity, it is a roomier bag allowing a person to comfortably don virtually all their clothing inside the bag. The Ultralite is more confined and makes this practice more of a challenge if not problematic. In other words, to remain in the spirit of the intent of this review, for me, given my physical stature, the Ultralite is number one. For a more robust/rotund person (who doesn't mind the half-zipper configuration), the Hydrogen might be number one. The mental gymnastics involved here are dizzying such that I've concluded that I'll give both the Ultralite and the Hydrogen a place in my gear closet, on the top shelf!
THREE-SEASON / MILD WINTER (10-20):
If you thought the Western Mountaineering Versalite would be a slam dunk here, you and I thought the same. The Versalite is such an incredible bag, I vacilated right up to the very minute that I published this review - going back and forth between the Helium and the Versalite. I love the Versalite. However, in the end the Marmot Helium is my choice. Granted, the Versalite is awesome and don't forget the new Mountainsmith Vision, also quite a nice two pound, 15 degree bag. You will get your money's worth with all three of these top-of-the-line, three-season lightweight bags.
The rationale for choosing the Helium includes a number of subjective and objective considerations. In addition to the reasons for the Helium winning the "BEST BAG (quality, design, comfort, weight)" award, its 1/2 zipper design is much less of a concern in the cooler weather and even an advantage in that there is less opportunity for cold air to seep into the bag thru the zipper track. It costs less and it packs smaller. Relatively speaking, this is an awesome three-season, mild-winter bag packed into a two-pound package. I like it!!
Here again, features might dictate your choice. If the 1/2 zip of the Helium isn't attractive, but you still have a limit of 2 pounds or under, try the Mountainsmith Vision. The Vision's 3/4 zip with double zipper provides better ventilation options. If a couple of ounces over 2 pounds is acceptable, try the full-zipper, 2 pound, 3.34 ounce Western Versalite.
OTHER NOTEWORTHY PICKS:
Realizing that the comparative analyses could continue almost indefinitely, I hereby declare it finished. Hopefully, all this info will either provide what you need or significantly supplement what you already know. At any rate, this is
THE END
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