5310-00-680-9106 (FFW100)
NSN 5310-00-680-9106 (NIIN 00-680-9106) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number FFW100 (Federal Specifications Promulgated, CAGE 81348).
NIIN assigned January 1963; DEMIL A (none required).