Well this is unexpected. Apparently, in the early postwar years, the U.S. military packed sleeping bags in giant sardine cans, opened with a key and everything, for use in emergency situations in cold weather areas. This Youtuber found one on ebay and opens it some 65 years after it was packed.
It looks serviceable, believe it or not.
A goose down bag with a light cotton shell and an internal zipper, aside from the aged patina, it looks like something you’d find in an REI today. According to Popular Mechanics, this bag was packed for the U.S. Air Force’s F-84 fighter pilots in the early 1950s, meant for service in alpine or arctic environments. Being sealed in metal meant that the bags would be guaranteed dry and free from mold and mildew when opened. Pretty ingenious, actually. And clearly a better preserver than the mesh sacks today’s sleeping bags come in. But my goodness, opening one of these cans with frozen fingers after crashing in Siberia, or North Korea, or somewhere like that could not have been much fun.