This small CO2 bottle fits into a small slot on the magazines used with the Maurer 70mm cameras that were used on the last four flights of the Gemini program. The purpose of the CO2 cartridge was to release gas to press the film against the plate at the focal plane at the moment of exposure to eliminate any curl of the film.
NASA transferred this CO2 bottle to the Museum in 1971.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.