A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6135-01-162-0943
NSN 4140-00-517-7902
NSN 5855-01-398-6170
NSN 6105-00-237-6292
NSN 6105-01-425-1718
NSN 5999-01-474-4886
NSN 5920-01-151-9117
NSN 6240-01-263-5343
NSN 5985-00-786-2321
NSN 6240-01-549-5405
NSN 5910-01-212-9659
NSN 5975-00-903-2770