In his post under Lite Gear Talk, Pika describes some lightweight backup sunglasses he takes along, and also why he takes them (because, at least once, his "real" sunglasses went sliding off the mountain and, since he has light-sensitive eyes, he doesn't want to risk snow blindness.)

That got me to thinking: as we all talk about strategies for lightening our load, we discuss multiple use gear. I think that implies an assumption that there will be no duplicate gear carried. However, I'm quite sure that, in fact, we all carry at least one piece of duplicate, "backup" gear.

I'd be interested to know what gear you carry a backup for, why you feel you can't risk being without that item, and perhaps what you considered taking backup for and decided you could make do without if necessary. Also, how much weight do you devote to such items? I don't consider a change of clothes or those longjohns you always carry for unpredictable weather to be backup gear.

For me, it's a spare lighter (or some matches, but not both), a spare hipbelt buckle, a spare LED light, some chlorine dioxide tablets, and a spare water filter element. Total weight is probably 4 or 5 ounces for the "stuff" and another 4 or 5 ounces for the windbreaker.

The lighter is so I don't have to eat cold freeze-dried food if I lose the lighter I keep in my cook kit (or forget to fill it before a trip.) It's also to light a fire, should one become necessary in an emergency situation.

The hipbelt buckle is purely peace of mind: I have this awful feeling that, someday, I'm going to step on my hipbelt and break the buckle. I've never done it; I'm almost paranoid about buckling it behind my back before I take the pack off, just so it won't lay flat on the ground, waiting to be stepped on. But, I often have Scouts with me, and as any Scouter can tell you, no mishap is beyond the ability of 12-year-old boys.

The spare LED is a Princeton Tec Pilot light that clips onto the webbing on my pack's shoulder straps. It's mostly so I have a light handy while hiking, and so I can see to change the batteries in my headlamp (for some reason, the batteries never die during the day.) However, it's also a backup in case I decide to calibrate my headlamp by dropping it on a rock, or in case I leave it laying on a log as I pack up to leave. I consider it essential to have a light if I should have to hike at night, or see to apply first aid or avoid getting burned while cooking in the dark.

The purfication tablets are there in case I have catastrophic water filter failure. You know: watching it float away down stream, dropping it (those pesky rocks again), having an indispensable plastic part break, etc.

The spare filter element may be temporary backup. I simply haven't used my Hyperflow enough yet to establish a confidence level; I've also seen one review on Backpackgeartest.org about the element threads disintegrating, and had a friend also have that happen to him. After I've worked my way through an element's life cycle of clogging, backflushing, and disassembly/reassembly, this piece of backup might disappear.

As I think about it, I suppose the scissors on my Swiss Army Knife might be considered backup for the scissors in my first aid kit. However, that's purely incidental. I carry the SAK because it has a screwdriver blade, which gets used to adjust the fit of the GG Nimbus Ozone packs the Scouts use. The scissors just kind of tag along. Maybe I'll pull the scissors out of the first aid kit...

That's mine. How about the rest of you?