A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6145-01-355-7192
NSN 5930-01-142-3325
NSN 6645-01-558-6229
NSN 5915-01-429-8328
NSN 6240-01-224-6941
NSN 5990-01-384-2697
NSN 6645-00-484-1992
NSN 6135-00-369-2368
NSN 5990-00-438-5587
NSN 6685-01-078-4886
NSN 5998-01-067-5338
NSN 4140-01-500-4563