I have a "black ice, 0 degree bag from Kelty but the thing is synthetic and it is also over twenty years old. Still works like the day I bought it. I would guess that 15-20 degrees would be a more accurate rating but then we all do want to be comfortable. This bag goes into a water proof stuff sack probably close to 8X12 inches. The bottom of the bag is round so it does keep a round shape at the bottom but I usually flatten it out so that it goes into my pack a little easier. sabre11004...