A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5998-01-386-2710
NSN 6650-00-583-1735
NSN 5915-00-889-6538
NSN 6135-01-495-0933
NSN 5835-00-289-9080
NSN 6145-00-528-6467
NSN 7035-01-359-7460
NSN 5925-01-008-8520
NSN 5930-01-576-9993
NSN 6110-01-111-0263
NSN 5960-01-010-8787
NSN 6150-01-180-4876