A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6150-00-683-0465
NSN 6150-01-328-8848
NSN 5925-01-317-0492
NSN 5998-00-488-2276
NSN 5945-00-702-0974
NSN 5985-01-411-0590
NSN 5990-01-107-1003
NSN 5945-00-213-0101
NSN 5905-00-753-0299
NSN 6645-01-642-3637
NSN 5920-01-423-8410
NSN 4140-00-444-9695