Mylar,Nylon TOUGHEST MYLAR SLEEPING BAG ON EARTH ? Our tear-resistant, extra-thick HeatFlex mylar is stronger and more flexible than ordinary space blanket mylar. We?ve added a hood section to protect your head and reinforced tape seams to create a durable, reusable survival bivy you can use alone or to enhance your existing sleeping bag. ENHANCE YOUR EXISTING SLEEPING BAG ? Worried about unexpected cold or wet weather? The DDITW Emergency Sleeping Bag reflects up to 90% of body heat to boost the heat retention of your sleeping bag, and the waterproof material protects your sleeping bag from outside condensation. BUILT-IN HEAD PROTECTION ? Studies show you lose up to 10% of body heat through your head. Our innovative hood design helps you retain this body heat for total body protection. This exclusive feature is only available from Don?t Die In The Woods. ULTRALIGHT, WATERPROOF, SUPER COMPACT ? Hate carrying extra weight? It?s so small and light, you?ll forget it?s even there. We?ve designed the DDITW Emergency Sleeping Bag with the perfect balance of durability weight at only 7 ounces (the weight of a small apple). Stash them in each of your cars and backpacks and always be prepared. PROTECT THE WILD PLACES WE LOVE ? We donate a percentage of profits to conservation efforts around the world, including 1% For The Planet, The Conservation Alliance, and many more. 100% SATISFACTION GUARANTEED ? We stand behind our products. You won?t find a tougher mylar survival bivy anywhere. Guaranteed. Emergency sleeping bag