Specially-produced stainless steel ball designed for use in an oxidizer flow ball valve in the Apollo Service Propulsion System (SPS) engine made by Aerojet General Corp., measuring approximately 2.5″ x 3.25″, marked on the side: "P/N 703615-13, J, S/N 0001318." The SPS engine was housed in the Service Module. This is one of eight balls used in the engine's ball valve that controlled fuel and oxidizer flow to the engine's injector. The oxidizer flow was slightly higher in volume than that of the fuel, matching the overall fuel/oxidizer mix in the combustion chamber: thus, the opening in the oxidizer balls was about 2″ while that of the fuel balls was slightly smaller, about 1.75″. Includes three ball valve seals/spacers as used within the system, all sealed in their original cleaning bags. In overall fine condition. Accompanied by a diagram of the system, showing the banks of eight ball valves (four on the oxidizer side, and four on the fuel side).
