A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5930-01-172-4552
NSN 6645-01-381-2050
NSN 5998-01-630-2250
NSN 5945-00-287-8022
NSN 5945-01-581-2755
NSN 6240-01-162-6749
NSN 5975-01-512-8525
NSN 5998-00-116-1330
NSN 6320-01-407-8663
NSN 5835-01-624-5666
NSN 6150-00-518-2743
NSN 6135-00-613-1068