US Army Modular Sleep System (MSS)

The MSS (Modular Sleep System) is a set of sleeping bags that the US Army has been using for a while. This is the sleeping system that I use, and while there have been many changes to sleeping bags since it’s conception, I have not been able to find a better value.

The MSS is not a single sleeping bag, but rather consists of two sleeping bags, a bivy cover and a stuff sack. When the two sleeping bags and the bivy are arranged in different combinations, the system can cover a wide range of temperatures and weather conditions. Each sleeping bag can be used separately or in combination with the bivy, or both bags and the bivy can be fitted together for a claimed temperature rating of -30F. All of the components can snap together to prevent sliding around.

Here are some of the specifications:

Patrol Bag (Green) features:

Temperature rating to +30F.
Reversible double-pull (opens end to end) slider allows top or bottom ventilation
Non-locking slide fastener self repairs if jammed or snagged
Draft flap prevents heat loss
Hood adjusts for heat retention; includes nylon drawcord and barrel lock
Measures 92 x 37 in to 92 x 24 in

Intermediate Cold Weather Bag (Black) features:

Temperature to -10F
Free from cold spots
Insulation does not migrate in the bag
Anatomically designed foot box contains twice the insulation as the bag
Sewn-in, quilted chest collar prevents air drafts up and down through the hood
Hood adjusts for heat retention; includes nylon drawcord and barrel lock
Measures 87 x 35 in to 87 x 23 in

Bivy Cover (Woodland Camo) features:

Made of durably waterproof and windproof 3-layer GORE-TEX fabric and approved by all

departments and agencies of the Department of Defense
Includes snap fastener and slide fastener
Measures 85 in x 28 in x 35 in

Stuff Sack features:

Compressible to one cubic foot
Six 1 in-wide nylon webbing straps adjust by ladderlock buckles
Reinforcement webbing is sewn around the circumference of the bag
Nylon drawcord closure with a barrel lock
Measures 30 in length, 14 in diameter

The big down side to the system is the weight and volume. The MSS weights about 13 lb and compresses to about 2 ft in length by 1 ft diameter. A big contributor to the weight is the fact that these are synthetic sleeping bags. Unlike with down bags, if you want to get into very low temperatures with a synthetic bag, you will pay with weight and volume.

That being said, the majority of both the weight and volume is contained in the black, intermediate cold weather bag. If you leave it at home, and take only the green +30F bag along with the bivy, the two will compress to a size of about 1 ft length by 7 in diameter.

Even so, you may ask why bother with synthetic bags, or any type of system at all. There are two answers. The first is that a synthetic bag will provide much greater insolation if it gets wet or moist than a similar down bag. That is probably a large part of why the US Army uses them-they are hard to mess up. The other reason is the cost. The whole system retails for anywhere from $250.00 to $400.00 (you are paying too much). Go try to find any two sleeping bags, and a bivy for that price.

However, be careful. There are many knock offs on the market. A genuine MSS can be recognized by the NSN #. Each item within the system will have a patch which provides the number along with instructions. Without it, it is not the real deal.

This product is not designed with comfort in mind, but rather brutal practicality. There are no mosquito nets, no head room, and no pockets. What you do have however, is a solid set of sleeping bags, which will keep you warm and dry.