A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-01-304-7597
NSN 5985-00-869-1041
NSN 4140-01-595-0741
NSN 6645-01-578-6815
NSN 5895-01-449-9638
NSN 6685-00-867-0475
NSN 4140-01-140-6781
NSN 4140-00-699-0904
NSN 5999-01-224-8589
NSN 4140-00-203-0419
NSN 5999-00-893-9466
NSN 5935-00-021-4863