A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5905-00-555-1899
NSN 5990-00-467-7431
NSN 6150-00-754-9911
NSN 5930-01-508-4393
NSN 5905-01-589-4854
NSN 6150-01-511-0262
NSN 6110-00-622-7478
NSN 5998-01-645-1895
NSN 2925-00-251-0105
NSN 5990-01-433-1471
NSN 6105-00-456-1433
NSN 5920-01-249-4544