A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6145-00-834-6378
NSN 5835-00-431-4451
NSN 4140-01-361-8883
NSN 5950-01-108-0599
NSN 5975-00-031-2871
NSN 5895-01-462-0648
NSN 5990-01-284-3187
NSN 5925-01-237-3886
NSN 5996-01-431-7716
NSN 6240-01-445-8011
NSN 5910-01-010-6475
NSN 6240-01-470-9322