A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6240-00-242-0003
NSN 5960-00-998-4324
NSN 5905-00-957-0196
NSN 5895-01-344-6136
NSN 4140-01-252-9502
NSN 6110-01-528-1489
NSN 5930-00-826-9702
NSN 6620-01-519-2628
NSN 6240-01-088-7629
NSN 5920-00-917-3539
NSN 4140-00-008-4912
NSN 5998-00-491-2591