A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6645-01-575-2297
NSN 5835-01-597-4820
NSN 5895-00-611-3168
NSN 6130-01-549-2932
NSN 6685-00-045-5243
NSN 5905-01-381-6386
NSN 6620-01-200-8176
NSN 5910-01-339-1423
NSN 6135-01-156-4627
NSN 6610-01-172-4041
NSN 6320-01-111-8851
NSN 4140-00-420-0251