A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-01-152-1936
NSN 6105-01-261-6681
NSN 5835-00-754-7255
NSN 6610-01-499-0776
NSN 6145-01-539-4681
NSN 5998-01-302-4015
NSN 5945-01-240-8062
NSN 5930-01-013-9188
NSN 5895-01-476-2041
NSN 5920-01-541-4258
NSN 6145-01-015-6934
NSN 5895-00-018-3231