A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5975-01-643-0532
NSN 6110-00-900-3970
NSN 5960-00-310-3844
NSN 6620-01-401-5356
NSN 6150-01-499-8803
NSN 5945-01-403-2800
NSN 5920-00-753-5113
NSN 5996-00-125-4570
NSN 5925-00-931-7659
NSN 6650-01-025-8803
NSN 5930-01-600-3429
NSN 5996-01-104-4161