The JIS B 1190 lock nut flange and the general JIS B 1190 hexagon nut are basically the same in terms of size and thread specification, but compared with the JIS B 1190 hexagon nut, the gasket and the JIS B1190 lock nut with flange are integrated, and there are anti-skid tooth patterns on the bottom, which increases the nut and the workpiece. Compared with the combination of ordinary nut and washer, this left-hand flange nut is firmer and has greater tensile force. The flange nut surface itself has the anti-slip and stop functions of the flat washer and the spring washer, so there is no need to add the flat washer and the spring washer during assembly, which will be counterproductive.
JIS B 1190 (ISO 4161) - 2005 Lock Nut With Flange - Coarse Thread
See details at its equivalent product: ISO 4161