A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-01-339-5524
NSN 7035-00-300-3208
NSN 5905-01-204-8574
NSN 5999-00-317-6262
NSN 5999-01-421-3388
NSN 5975-00-500-0166
NSN 6220-00-414-7528
NSN 6645-00-614-5302
NSN 5998-01-370-8274
NSN 5835-00-931-5568
NSN 5985-01-536-1677
NSN 6150-01-509-6384