The New Mil-Spec Plus 3 Bags In One Modular Sleep System consists of 2 lbs. of hollow fiber filled double layer outer mummy bag, with matching stuff sack, patrol bag with 1.5 pounds of hollow fiber fill that serves as a liner or removable light weight sleeping bag by itself, and an oversized O.D. nylon compression stuff sack for the entire system. Outer bag can be used alone, while the patrol bag is designed for use in temperate climates as a single bag or to be inserted inside the outer bag to create the modular system. Color is for the exterior bag. Inner bag will be black or OD. Temperature rated 10 - 20 degrees!