this worked well for an emergency situation. I have used this on a survival campout when in scouts and it worked well but dont plan on using this as a warm substitute for a real sleeping bag the durability for it is questionable

used it when overnighting at 9500 feet in 30+ mph winds. Very warm, very durable, won't ever leave home without it.

Great piece of "OH SH!T" gear. Light enough to carry everywhere, small enough to fit in any pack. When you need it you will be happy. The bag design is many times better than the blanket. Dont waste your time with a blanket, get this bag.

This may be the smallest/lightest piece of gear that has the greatest potential to save your life in a not so uncommon emergency... getting stuck in the wilderness overnight without shelter. If this situation occurs in mild conditions, this bivvy will keep you from mild hypothermia. However, if you're backcountry mountaineering and SOL stuck in a surprise storm this little fella can mean the difference between surviving and not.
Also, I think it's superior to the emergency blanket because your body is sealed from the elements, instead of having to worry about gaps.

I have used a product similar to this while in Special Forces in the mountains of Afghanistan in the winter. It is an unforgiving envionment with the proper gear. Our tactical situation demmanded the we "go light." This means that you strip a strip a special bag off your about, 200lb pack, which contains only essentials (contents classified.) You blow the packs with C-4 and bugout. One item (unauthorized, but we all got them) in the bag is a thin, silverized on one side and OD Green on the other. You place the silver side towards the body and huddle together. Granted, it is no super sleeping bag, there were a few tears; but all of us lived until extraction. For those who critisize them try to think and remember, they are emergency devices, not your 1K fart sack.