Apollo Helium RCS check valve assembly used in both the command and service modules. Lightweight check valve assembly for the Reaction Control System measures approximately 4.5″ long. Data stamped on the part indicates it was made by Accessory Products Company under order number NAS9-150, which was the NASA contract number of North American Aviation, which built the command module. Accompanied by its Accessory Products paperwork indicating that the part was made on September 6, 1964. In fine condition. RR Auction COA.