A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5920-00-948-9071
NSN 5835-01-366-5907
NSN 6240-01-224-6941
NSN 6135-00-702-2772
NSN 5996-00-413-4416
NSN 5930-00-132-6519
NSN 6645-01-537-3114
NSN 5905-01-063-8268
NSN 5910-01-467-4356
NSN 6240-00-959-7025
NSN 6320-01-162-5977
NSN 6135-01-230-4399