A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-01-541-7671
NSN 6610-01-565-9857
NSN 5920-01-307-1439
NSN 6620-01-179-6010
NSN 5960-01-372-3290
NSN 6130-01-400-3651
NSN 5996-00-877-3278
NSN 5905-01-325-3209
NSN 5985-01-398-9580
NSN 4140-00-456-0902
NSN 6650-01-484-3013
NSN 5930-01-563-9098