Screws And Bolts Product description Medium-Strength Metric Class 8.8 Steel Square-Neck Carriage Bolts These Class 8.8 steel bolts are suitable for fastening most machinery and equipment. They have a zinc or zinc yellow-chromate plating to resist corrosion in wet environments. A square neck keeps them from turning when tightening a nut. A smooth, rounded head provides a finished look. Length is measured from under the head. Product detail Head typeRounded Rounded Head StyleCarriage System of MeasurementMetric Thread DirectionRight Hand HardnessRockwell C22 Thread SpacingCoarse Grade/ClassGrade 8.8 FinishZinc Yellow-Chromate Plated Steel,Blue White Zinc MaterialMedium Carbon steel StandardDIN603,ISO8678 Product drawing Quality control process Production workshop Packing and shipping Screws And Bolts website:http://www.xgf-hardwares.com/screws-and-bolts/