All-Metal Hex Flange Prevailing Torque Lock nuts in Zinc Plated Steel. Metric DIN 6927 and have a Class 8 rating and have a standard coarse thread. RoHS compliant Cr+3 zinc plating. Flange acts like a built in washer to distribute the load.
Nut Size is the size of the screw that the nut is for (M8 nut for a M8 screw).