Hexagon thin slotted and castle nuts – Metric coarse and fine pitch thread – Product grades A and B
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 10/01/2000

Hexagon thin slotted and castle nuts – Metric coarse and fine pitch thread, product grades A and B
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 08/01/2013