Armstrong's 7 Piece 3/8" Drive Metric Hex Driver Socket Set comes with bits manufactured to the highest tolerances and specifications for straightness, concentricity, and precise tip fit to the fastener. They are manufactured from high alloy steel using the most up-to-date manufacturing process and heat treat to prevent shattering and premature bit wear. The bits are retained in the bit holder by a set screw that locks securely into a groove on the bit for positive bit retention as well as simple, easy bit replacement. Broached hex in the bit holder allows higher torque loads while EYE-D™ marking optimize size visibility.