Military rifleman sleeping system. Defence 4 sleeping bag Plus Tropen sleeping bags, 2 bags in one Bivy Nylon Taslon Compression Sack. The sleeping bag which can be used alone or combined into a sleeping bag system. The shell of the sleeping bag is made of nylon Taslon material, which is waterproof. The inner is made of G-loft cotton, breathable, temperature-regulating, moisture-wicking and light and airy at the same time. What makes G-LOFT cotton so special? Insulates like down with absolute dimensional stability. Incomparably light and airy. Optimal ratio of heat output to weight.