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 4140-01-596-3857
NSN 6610-01-287-3678
NSN 5965-00-950-0602
NSN 7035-01-645-9018
NSN 5985-00-269-5388
NSN 6645-00-802-7991
NSN 5990-00-254-4825
NSN 5895-00-686-7772
NSN 5945-01-540-7794
NSN 5925-01-627-5464
NSN 6240-01-232-4408
NSN 5920-01-388-6533