Rocketdyne J–2 engine helium release valve, 2.5 x 1.75 x 2.75, with two Rocketdyne inspection seals and the main cylinder labeled with part numbers, “551363 Assy, S/N N7261205, Valve Assy., Spec. NA5–27273t1–3, Rocketdyne, MFG 1–7–70” and “69BB453–2.” Red plastic base is engraved, “ST3950272RKLO11,” and labeled “02602” and “MFR08790.” Includes original Rocketdyne tag with NASA and North American inspection stamps and matching part numbers, as well as the original plastic bag with matching part numbers and date. The J-2 engine powered the second (S-II) and third (SIV-B) stages of the Saturn V rocket that took astronauts to the moon. Given how helium was used to power fuel bleed valves on the J-2, this important electrically operated valve opened to release excess pressure from the J-2's integral helium tank. In fine condition. Valve is unused and the previously sealed packaging was opened for inspection and photography only.