6-point hex socket for maximum torque transfer to the face of the fastener. Precision cold-forged, hardened and tempered chrome vanadium steel. Fully polished and nickel chrome-plated for durable corrosion resistance. Chamfered ends and thin walls for positive location on fastener. Knurled ring provides grip and control, and bearing hole provides solid connection to the tool. Contents: 5, 6, 7, 8, 9, 10, 12 and 13mm.