The commercial upright Carpet Pro CPU-4T is lightweight, powerful and includes many convenient features. The motor on the Carpet Pro CPU-4T is By-Pass which means all of the dirt goes directly into the bag and NOT through the motor. This means you can pick up a nickel or screw and not worry about braking a set of fans which is a common problem in many other commercial machines. The exhaust filter helps clean the air that is expelled from the machine.