A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6685-01-332-7822
NSN 5960-01-624-1170
NSN 6645-01-322-8431
NSN 6650-00-316-4889
NSN 6220-01-443-7731
NSN 5925-01-420-6924
NSN 6105-01-017-9077
NSN 6240-00-175-9104
NSN 6130-01-054-9669
NSN 5998-01-322-9477
NSN 5990-01-476-9956
NSN 5985-01-532-0150