This pocket was attached to the lower leg of the spacesuit worn by astronaut Thomas P. Stafford, Lunar Module Pilot of the Apollo 10 mission of May 1969. Apollo 10 was a "dress rehearsal" for the lunar landing missions.
The number of pockets worn was a personal preference of the astronauts. The pockets were attached to the suit through loops with velcro and a buckle, and closed with additional velcro fastners.
NASA transferred this pocket to the Museum in 1975.