The Jet JAT-121K 1/2" Impact Wrench Kit (505121K) features a high quality tool that's rated to last for those demanding, 12-hour days. This impact wrench comes standard with an ergonomically designed grip that reduces user fatigue and keeps you working longer. The patented, twin hammer impact mechanism is excellent for heavy-duty applications and provides instantaneous, balanced torque that delivers more power per pound. Its upgraded motors increase durability and reliability of the air tool and the four-position speed selection switch allows for easy adjustment of torque settings.