A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5935-01-157-3463
NSN 4140-01-139-4041
NSN 6320-00-521-9350
NSN 5996-00-769-5112
NSN 5950-01-461-1216
NSN 6145-01-333-6280
NSN 5930-01-464-4989
NSN 6610-00-902-7398
NSN 5925-00-111-5063
NSN 5920-01-051-6638
NSN 6135-01-407-8254
NSN 6105-00-015-5183