Carry it as a winter survival precaution or as an ultra light alternative to a summer-light sleeping bag, either way the Adventure Medical Kits Thermo-Lite 2 Bivy takes up very little room in your pack, boat, or snowmobile. The Thermo-Lite 2 bottom is 30% stronger than previous versions, and Velcro openings on the top and side allow for escape of excess heat and moisture vapor.