Full 4-Piece Modular Sleeping System – Military Style Includes Patrol Bag, Intermediate Bag, Waterproof Bivy Cover, and Compression Sack. Adaptable for All Seasons – Use Separately or Combined Rated down to -30°F when fully layered; can be used individually in warm weather. Durable, Water-Resistant & Windproof Materials Outer bivy cover made from waterproof breathable fabric; inner layers filled with warm synthetic insulation. Military-Grade Function – Field-Tested Performance Designed for harsh outdoor conditions: cold, wet, or windy. Available in 4 Tactical Colors Choose from Woodland, Multicam, OCP (Scorpion), or Olive Drab to match your gear and terrain. MT Military Modular Sleeping System. MT military modular sleeping bag system =summer thin sleeping bag jacket +spring autumn sleeping bag+ winter low temperature sleeping bag + winter or high mountain sleeping bag. It can be used in conjunction with each other or separately. The large Stuff Sack is made of waterproof Nylon and it can hold both the Patrol sleeping bag and the Intermediate cold weather sleeping bag as well as the Bivy Cover.