An air impact wrench or pneumatic impact wrench is an air tool that is designed to remove and tighten bolts and nuts at speed. Air impact wrenches differ from the other types of powered wrenches as they can deliver torque in instantaneous jolts instead of using a steady force.
For the tool to work it makes use of a strong twisting motion in order to free stubborn bolts or fasteners that have become too tight or have developed rust over time. The multiple sharp and short torque applications can remove even the most stubborn fasteners.
The models can differ in terms of their weight and torque, each of which can make a great difference when it comes to the usability of the tool.
Air impact wrenches have various competitors as far as the drive mechanisms are concerned. The hydraulic impact wrenches are now used in several industrial applications wherein there is pressured hydraulics available yet the more famous among the home users is the electric impact wrench.
You can even possibly get the cordless electric variants but these typically have low power as compared to the more heavy duty counterparts. The kind of wrench that you will use will depend on the circumstances and the content. If you are a hobbyist who needs a portable tool, you might want to go for the cordless version but if you are a serious professional, you might be better off with the more powerful air impact option.
The air impact wrench is definitely a helpful tool that can be used for removing those difficult bolts or nuts. There may be some alternatives but at the end of the day, your choice will still depend on your specific needs. The suitability of the tool that you will choose for a specific task or project that you have in mind is all that matters.
source: Air Impact Wrench Guide