A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-00-408-3519
NSN 5905-01-509-0138
NSN 6685-00-113-1888
NSN 6145-00-290-3859
NSN 5920-01-164-8260
NSN 6130-00-248-7244
NSN 6240-01-506-2059
NSN 5935-00-204-9909
NSN 7035-00-946-2642
NSN 5930-00-837-1245
NSN 6145-01-138-7323
NSN 6240-00-779-3394