Robust screw driving! Chrome-molybdenum steel for resistance to high torque. You can use the PRO Impact socket attachment for hex screws, bolts, and nuts with your square drive wrench. We designed it for screw work in extensive assemblies or other demanding industrial tasks. The PRO Impact socket attachment is made from heat-treated CRMO (chrome-molybdenum) steel and is very resistant to high torques thanks to its thick walls. The black phosphate coating protects it from rust and corrosion. The socket attachments are laser-etched and color-coded, so you can easily find the right one at a glance. They feature a groove and a through hole. For extra strong hold, they can be secured to your impact wrench with a pin and ring.