A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-244-9268
NSN 6220-01-244-2411
NSN 5910-00-170-5223
NSN 5895-01-070-7020
NSN 6240-01-359-2721
NSN 6145-01-151-9955
NSN 6320-01-101-5816
NSN 5960-01-450-8539
NSN 5999-00-259-7103
NSN 6150-01-312-1867
NSN 5996-01-106-1074
NSN 6620-00-963-1319