Ingersoll Rand 231C 1/2 Super-Duty Air Impact Wrench - The classic IR231 is the most popular tool in its class. Introduced over 25 years ago and continuously refined, it offers the sheer power and performance features to tackle the toughest jobs with ease as well as proven durability and economy. Exclusive impact mechanism Pressure-feed lubrication Adjustable power regulator Easy to service two piece construction Contoured handle for comfort and control