A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5895-01-461-7998
NSN 6685-00-115-2255
NSN 6130-01-213-0196
NSN 6240-00-134-9094
NSN 6685-01-550-7126
NSN 5965-01-256-6745
NSN 6320-00-905-0543
NSN 5998-01-631-7538
NSN 6650-00-775-6560
NSN 5985-00-617-5769
NSN 6110-01-422-5139
NSN 4140-01-258-1215