I never thought about taking an emergency blanket along on my winter trail runs. But one cold February morning a friend broke her ankle after slipping on the ice-covered trails. By the time we got help she was hypothemic and shaking like crazy. Now I always carry a foil blank on winter runs. It could be a life saver.

I've never used these for its true purpose as an emergency heat blanket. I use it more as a ground sheet for when I am using a tarp tent. It reflects the heat/cold so you stay warmer at night and keeps you dry when the ground is wet. For $16 bucks it is a great substitue for a heavier ground sheet.

These are tiny and are reusable. I bought a bunch of these and threw them in all my packs...just in case. I have not used them and hope I don't have too:)

Great piece of gear - comes cheap and has unlimited amount of uses.

I am not sure that I was in danger, but I was definitely more comfortable while using this bivvy on two trips (multiple nights each trip). I was in an open boat and used it while getting a few hours sleep. Without it I was shivering mildly and could not get any rest I. I really like that it is orange on the outside so that it can double as a large signal device.

I take this with me on all trips in case of emergency - hopefully I never need to use it. The size is roughly shorter than a soda can and slightly wider so it is nice and small and light weighing in at 3.5oz