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 7035-01-590-6755
NSN 6145-00-284-1514
NSN 6150-00-827-9005
NSN 6645-01-227-2036
NSN 6240-00-156-1607
NSN 6105-01-100-9871
NSN 6685-01-544-4795
NSN 5998-01-224-3962
NSN 5960-00-522-5231
NSN 6105-01-244-9373
NSN 7035-01-013-9889
NSN 5950-01-323-6507