A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-444-0971
NSN 5895-00-153-2595
NSN 6150-01-081-8698
NSN 5910-01-525-8728
NSN 5905-00-689-8027
NSN 5915-01-283-4430
NSN 6145-01-381-0708
NSN 5920-01-383-7108
NSN 6130-00-231-3929
NSN 6110-01-328-0646
NSN 6105-01-234-6611
NSN 5855-01-570-9714