The water repellent sleeping bag case is made of poplin and provides a wind-resistant cover for the sleeping bag. It is ordinarily used with all sleeping bags. In warm weather, when little protection is needed, the case may be alone. Two openings in the seam at the foot of the case allow the tie straps on the sleeping bag to to be drawn to the outside to hold the items in a compact unit when rolled. It weighs 1.88 lbs.
Military specification MIL-C-44307 covers one type and size of moisture vapor permeable bivy cover for attachment to the sleeping bag component of the extreme and intermediate cold weather sleeping systems.