The Therm-A-Rest Self-Inflating Sleep mat is a US Government Issue item that accompanies the conventional Military Sleep System. the mat will come with a simple repair kit, for quick fixes in the field. It features a self inflating valve that when open, fills the unrolled sleep mat with air. Once full, closing the valve keeps air trapped inside the mat, ensuring a comfortable barrier between the body and ground. It duly acts as an insulator, keeping your body heat from transferring to the cold ground.