A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5915-01-204-0005
NSN 4140-00-089-0490
NSN 6240-01-131-3223
NSN 5920-01-076-5870
NSN 6685-01-381-6016
NSN 5950-01-144-9969
NSN 5895-01-534-2506
NSN 5855-01-031-4729
NSN 5999-01-291-9432
NSN 6610-01-393-1141
NSN 5925-01-173-7286
NSN 5975-01-069-2196