A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5835-01-629-2044
NSN 6240-00-483-1338
NSN 5996-00-126-6139
NSN 5975-01-534-8990
NSN 6135-01-177-3552
NSN 6105-00-104-4395
NSN 6135-01-527-4669
NSN 5855-00-631-4565
NSN 4140-01-225-1412
NSN 2925-01-525-8212
NSN 5990-00-348-1423
NSN 5975-01-260-3642