A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6645-01-250-2702
NSN 6110-01-431-5770
NSN 5835-00-794-7500
NSN 6130-01-055-1574
NSN 4140-01-147-2164
NSN 5975-01-437-8869
NSN 5950-01-351-4386
NSN 5975-00-273-0790
NSN 6645-00-927-8207
NSN 6610-01-521-9801
NSN 5905-00-296-8763
NSN 5910-01-189-9659