A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5999-01-459-0424
NSN 5925-00-290-4451
NSN 6220-01-378-3488
NSN 5990-01-395-4194
NSN 6130-00-794-8653
NSN 5855-01-165-6361
NSN 6685-01-112-0524
NSN 5985-01-454-2437
NSN 6320-00-228-5678
NSN 5960-01-238-7367
NSN 5990-00-402-1715
NSN 6145-00-824-5910