A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5910-01-367-1788
NSN 6620-01-451-0066
NSN 6240-01-309-1426
NSN 6645-01-541-2425
NSN 5855-01-409-1792
NSN 5985-00-248-4978
NSN 5965-00-249-6980
NSN 5950-00-020-5570
NSN 4140-01-612-6852
NSN 5925-01-044-5508
NSN 6645-01-067-4081
NSN 4140-01-337-0495