A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-01-578-7561
NSN 5905-01-301-2899
NSN 5925-01-107-1951
NSN 5920-01-031-5397
NSN 5996-01-273-5483
NSN 6610-01-312-8340
NSN 4140-00-442-0556
NSN 5895-00-450-3130
NSN 5990-01-004-6343
NSN 5950-00-294-9554
NSN 6135-01-397-6564
NSN 5965-01-492-9344