Protective cover assembly for the torsional ring on a 1968 Rocketdyne J-2 engine oxidizer duct, measuring 14.25″ x 9″ x 5″, with cover bearing a stenciled Rocketdyne part number, "ST 3950020 RKL 012," a “Do Not Destroy” Rocketdyne label, and an affixed plastic pouch with credit requisition sheet dated September 9, 1970. The cover is also stamped “02602, MFR35070,” and the underside of the duct features a second Rocketdyne part number: "ST3950020RKL010." In fine condition.