A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-01-591-8797
NSN 5975-00-259-0267
NSN 6320-00-583-3105
NSN 5960-01-512-0233
NSN 6110-01-152-2840
NSN 5998-01-064-5070
NSN 5930-00-263-2582
NSN 6610-01-160-3770
NSN 6130-00-079-1269
NSN 6130-00-541-8468
NSN 5965-01-324-2441
NSN 5915-01-021-1646