A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-512-2031
NSN 5985-00-426-2548
NSN 5999-01-416-9229
NSN 5835-00-518-2740
NSN 6130-01-179-6624
NSN 6240-01-157-9128
NSN 6150-01-409-2858
NSN 5950-01-517-5112
NSN 7035-01-472-5762
NSN 6320-00-682-3448
NSN 7035-00-275-5604
NSN 5975-01-419-5931