When you're in an emergency situation, it's important to stay warm. The Emergency Sleeping Bag is made of lightweight Mylar material that reflects 90% of body heat back toward the user while protecting against wind and rain for up to 12 hours at a time. They fold up into the size of a small cell phone so they can be easily stored in your pocket or backpack for emergencies. With this emergency sleeping bag, you can keep warm and safe from the elements until help can find you. The advantage when compared to the emergency blanket, the sleeping bag doesn't have an opening on the bottom where heat can escape.