GearWrench 84940 1/2-Inch Drive Impact Hex Socket Set Metric, 7-Piece Chrome Molyebdenum Alloy Steel (CR-MO) For Exceptional Strengh and Durability Pin hole for use with pin and o-ring for secure socket retention Black Phosphate Coating to Resist Corosion High Visiblity Laser Etched Markings Secondary Hard Stamping-Part and Size