This tough Ingersoll Rand air impact wrench is great to have around the auto shop. Its twin hammer impact mechanism is durable and it boasts an easy-to-use adjustable power regulator for control. Hammer Mechanism: Twin, Working Torque (ft.-lb.): 25-300, Reversible: Yes, Variable Speed: Yes, Impacts Per Minute (IPM): 1,300, Inlet Size (in.): 1/4, Max. Reverse Torque (ft.-lbs.): 500, Max. Torque (ft.-lbs.): 500, Drive (in.): 1/2