Flat corners at the tip of the hexagonal bar are chamfered equally on each side. Easier to insert into the hexagon socket hole, and the chamfer angle is considered to be in close contact with the corner edge of the hexagon hole base.The hardness is HRC54 to 59.You can turn the screw from the angle of 25 maximum.Opposite Side Dimension (mm):3.0Length Excl. Head (mm):20Total Length (mm):71Chrome Vanadium Steel