Keep Warm! You can use this to slip inside your current sleeping bag as a liner for nights it gets too cold, or use it as a sleeping bag by itself. Made of metallic and polyester fabric, the Ready Hour Emergency Sleeping Bag is compact, lightweight, durable, wind resistant, and long lasting. It also retains body heat, which keeps you warm no matter the conditions you are facing. The Ready Hour Emergency Sleeping Bag also makes great ground cover, a makeshift tent, or an emergency blanket.