... 3.mechanical grade:8.8/10.9/12.9 4.case hardening:HRC38-HRC42 raw material40Cr,35CrMosize1/2''--1. ... 1/4,M12--M36Colorblackgrade10.9/12.9handnessHRC35-42(BOLT),HRC29-36 ... lock washers, structural Washers. square washer, bowl washer.Screws: machine screws, self tapping screws, self drilling screws, set screws, ... You M12-M36 and 1/2''-1.1/4'' roller bolt