A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-01-625-2804
NSN 5935-01-139-4267
NSN 6620-01-470-9861
NSN 5945-01-454-1614
NSN 5855-00-797-8217
NSN 6685-01-012-5406
NSN 5835-01-202-9673
NSN 5925-00-624-7415
NSN 6610-01-304-3226
NSN 5895-00-065-8619
NSN 7035-01-294-2688
NSN 6105-01-318-5734