A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-00-553-8854
NSN 2925-01-406-7837
NSN 5935-01-453-1138
NSN 5925-01-149-3066
NSN 6110-00-333-2160
NSN 5960-01-067-3156
NSN 5910-01-152-8656
NSN 5999-00-020-3322
NSN 5930-00-899-5004
NSN 5990-01-411-5930
NSN 5905-01-183-6292
NSN 5855-00-912-3885