A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-259-3927
NSN 6240-00-968-9274
NSN 6220-00-107-1835
NSN 6110-00-849-2549
NSN 5915-00-633-1217
NSN 5895-00-805-9179
NSN 5990-01-419-0661
NSN 6320-01-056-1164
NSN 6620-00-816-9755
NSN 6145-01-055-6340
NSN 5915-00-267-9857
NSN 7035-01-193-2667