The Survive Outdoors Longer® Emergency Bivvy is made from the same heat-reflective polyethylene as Adventure Medical Kit's world-famous emergency blankets (reflecting 90% of your body heat back to you), with the added benefit of being fully sealed so that no wind, rain, or snow can get inside. If you're forced to spend the unexpected night outdoors, hop in the Survive Outdoors Longer® Emergency Bivvy as soon as the temperature drops and instantly improve the odds in your favor.