This is an Extravehicular Activity pouch flown on the Gemini XII mission. This mission, the last in the Gemini program, carried James Lovell, Jr. and Edwin Aldrin, Jr. into space in November 1966. The pouch was probably used by Aldrin during one or more of his three spacewalks to carry tools and other necessary items. Its manufacturer is unknown.
NASA transferred the pouch to NASM in 1968.