A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-00-144-7201
NSN 6645-00-343-9919
NSN 6110-01-214-2397
NSN 6240-01-633-9357
NSN 5915-00-948-2900
NSN 6220-01-486-9591
NSN 6620-01-242-9247
NSN 6620-01-111-5847
NSN 5910-01-233-2052
NSN 5945-00-682-4375
NSN 2925-01-474-3363
NSN 5996-01-482-2214