Catalog calls this: metric spring - din 127b lock washer
A washer which is usually round with a centrally located hole. Its edges and two bearing surfaces are so designed that applied pressure brings into play the spring tension and/or frictional locking principle which materially resists any tendency toward turning. It may be made of one or two pieces
Classification: Spring washers and other lock washers, iron or steel
NSN 6110-01-326-9708
NSN 2925-00-338-4667
NSN 6620-01-412-0938
NSN 5855-01-229-3864
NSN 6135-01-205-5965
NSN 5998-00-189-0761
NSN 6645-01-076-4655
NSN 2925-01-020-5099
NSN 6130-01-456-0380
NSN 5915-00-893-2415
NSN 6620-01-174-9575
NSN 5945-01-021-0777