Most makes of impact wrenches look very similar. Prices may however differ. This is mostly due to the quality of the impact mechanism. If the tool is only used sporadically, then it is advisable to buy a low cost model, if the tool is going to be used frequently then the industrial quality models become interesting. Manufactured with stronger materials and better quality impact mechanisms, they guarantee a longer, more durable and trouble free lifetime.
Low cost tools are mostly executed with the single hammer impact mechanism. The industrial ones however, have a pin-clutch (Dynapact) or twin hammer system. Noise, vibration and weight also influence the price.
An industrial wrench has a better silencer and less vibration. In tyre workshops where impact wrenches are used continuously, these are the most important factors. Nowadays, modern impact wrenches are executed with a rear exhaust (outgoing airflow through the hand grip), while many of the conventional wrenches have an exhaust situated at the front of the tool. This can cause brake dust in the face of the operator during the process of untightening wheel nuts. Highly uncomfortable!
Often people think that the specified torque level of an impact wrench equals the performance of the tool, this is not correct. Impact wrenches can not be compared on the specified torque only, as there is no standard for measuring the torque. The specified torque depends on various influences: the impact mechanism, weight, air consumption and quality.