A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6110-00-106-6587
NSN 5960-00-602-9906
NSN 6150-01-328-8220
NSN 6105-00-664-1292
NSN 6105-01-515-0613
NSN 6645-01-432-7026
NSN 7035-00-470-4977
NSN 5950-00-833-4608
NSN 5985-00-932-5333
NSN 5960-00-713-7394
NSN 4140-01-548-4906
NSN 6220-01-645-1759