A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6110-01-219-0135
NSN 6130-01-063-7446
NSN 6220-00-079-0851
NSN 6650-01-231-6728
NSN 2925-00-928-5931
NSN 6620-00-085-2908
NSN 6220-00-860-5292
NSN 5835-00-794-7500
NSN 5855-01-184-8089
NSN 5998-01-198-1300
NSN 6620-01-627-0478
NSN 6150-00-900-2371