A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5935-01-654-5928
NSN 5945-00-554-9351
NSN 5975-00-247-1230
NSN 5999-01-056-5281
NSN 6620-00-425-7475
NSN 5895-00-231-3977
NSN 6610-01-027-1641
NSN 6645-01-412-4233
NSN 5975-00-401-5365
NSN 4140-01-464-3231
NSN 6110-01-534-4933
NSN 5905-01-578-8399