Robust screw driving! Chrome-molybdenum steel for resistance to high torque. You can use the PRO Impact Socket Set 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 Set 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 sockets 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 grip, they can be secured with a pin and ring to your impact wrench.