A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-01-149-8354
NSN 5895-01-594-3027
NSN 5905-01-333-1143
NSN 5950-01-229-7484
NSN 5895-01-532-3502
NSN 4140-00-391-0879
NSN 5985-01-322-1467
NSN 5975-00-951-6573
NSN 5935-01-578-7979
NSN 6150-01-187-4255
NSN 5935-01-394-0733
NSN 5999-01-478-7741