A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-425-1417
NSN 6105-01-408-6597
NSN 5905-01-018-4530
NSN 5996-01-202-8605
NSN 5975-01-649-7476
NSN 5920-01-103-3655
NSN 6685-00-157-3289
NSN 5998-00-406-4413
NSN 5950-01-312-8192
NSN 4140-00-792-6584
NSN 5999-01-426-3213
NSN 6645-01-110-0776