SHOCKWAVE™ IMPACT DUTY steel (Chrome-Molybdenum) is high quality alloy steel which provides ultimate strength and durability. According to DIN 3129 / ISO 2725-2, internal square drive according to DIN 3121 / ISO 1174-2. 6 gripping points for precise fitting. Recessed corners allow torque to be transferred across the flats of the socket rather than producing stress on the points or corners. Deep wall construction provides clearance for protruding bolts. Laser etched size markings for easy identification and won‘t wear off.