A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-01-434-1707
NSN 7035-00-631-3782
NSN 5990-00-522-3425
NSN 6110-00-785-7927
NSN 6105-01-499-2430
NSN 5905-01-503-4034
NSN 6320-01-111-8851
NSN 5915-01-505-3730
NSN 5999-00-417-8187
NSN 6610-00-401-2601
NSN 5855-00-832-9341
NSN 2925-00-149-0760