Hypothermia is the number 1 cause of death in the alpine environment. The best way to warm up is probably by stripping down and cuddling up with your part inside a double sleeping bag on top of a good camping mattress. This technique has saved many lives but if you’re alone, the Thermo Lifewrap could be your only lifeline. You can also use it as a rescue equipment to sustain a victim’s life while being transported for treatment.
My only suspicion is if the battery would work in extremely low temperatures.