M-1945 arctic sleeping bag consists of two sleeping bags: outer casing and inner casing. Both have full-length opening with zipper and eyelets for lacing the water repellent case.
M-1945 mountain sleeping bag is identical with inner component of M-1945 arctic sleeping bag.
The M-1949 arctic sleeping bag consists of two mummy-shaped sleeping bags: outer bag and inner bag. It is for use in temperatures of 14°F and below.
The M-1949 mountain sleeping bag is intended for use in locations where temperature ranges from 14 to 50°F.