5310-00-515-9953 (FF-W-84)
NSN 5310-00-515-9953 (NIIN 00-515-9953) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number FF-W-84 (Federal Specifications Promulgated, CAGE 81348); also referenced as FFW84CLASSASTYLE25-8INWASHERL0CK (Federal Specifications Promulgated).
Key specs: 45 to 53 rockwell c hardness; full characteristics table below. NIIN assigned January 1963; DEMIL A (none required); ships at 2.38 lb / 0.0225 cu ft. Related NSN 5310-00-820-6653.