A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6130-01-438-6291
NSN 5910-01-421-3007
NSN 5975-01-413-2474
NSN 6220-01-057-7365
NSN 5998-01-412-0340
NSN 6220-01-221-7748
NSN 5990-01-423-8189
NSN 5996-01-533-3219
NSN 6220-01-503-7216
NSN 6105-00-973-7247
NSN 6150-01-211-3345
NSN 5999-01-100-0921