This U.S. Military Cold Weather Sleeping Bag is the inner bag component of the legendary MSS (Modular Sleep System). More specifically, the updated post-2007 improved version. Completely usable on its own for comfort in temps down to -10ºF. Combine with the original issued patrol bag (not included here) and stay cozy down to an astounding -30ºF. Because this is the "improved" version, this Bag is even lighter than the original, weighing in at only 4 lbs.