This outer window retainer formed part of the window assembly in the left-hand hatch above Jim Lovell’s head in the Gemini XII spacecraft.Commanded by Lovell and piloted by Edwin "Buzz" Aldrin, Gemini XII was launched on November 11, 1966 for a 4-day, 59-orbit mission. Highlights included 3 extra-vehicular activities (EVAs) by Aldrin, 5 hours 30 minutes total, in which he evaluated improved EVA techniques to manage workload and overheating during EVA. Aldrin made extensive use of handholds and footholds to prevent unwanted movement during his tasks, and his techniques were an important milestone toward effective astronaut use of EVA. During one of the spacewalks, Aldrin attached a tether to the docked Agena 12. The tether allowed the crew to create an artificial gravity by separating the Gemini from the tethered Agena and firing thrusters to induce a slow spin.

NASA transferred the Gemini XII spacecraft and the window retainer to the Smithsonian in 1968.