A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-01-053-5115
NSN 6320-00-242-3300
NSN 5950-01-143-1062
NSN 6150-01-609-7124
NSN 5925-01-419-4858
NSN 6240-01-411-5630
NSN 6110-00-185-8147
NSN 5915-01-069-2775
NSN 5915-01-492-6600
NSN 5910-01-219-6758
NSN 5915-00-919-8522
NSN 5905-00-105-0792