5310-00-511-9049 (78-357)
NSN 5310-00-511-9049 (NIIN 00-511-9049) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number 78-357 (Borg-Warner Corp, CAGE 96152).
Key specs: case-hardened; 70 to 85 rockwell b hardness; full characteristics table below. NIIN assigned January 1963; DEMIL A (none required).