A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6150-01-556-6438
NSN 6240-01-479-9333
NSN 7035-01-063-0453
NSN 5950-01-579-4485
NSN 5990-01-493-4039
NSN 5990-00-464-6385
NSN 6610-01-583-6466
NSN 5935-00-886-1650
NSN 5905-00-325-2122
NSN 5910-01-599-9338
NSN 6135-01-205-5965
NSN 4140-01-417-2611