The Centec Quiet Drive CT18DXQS features a 14 inch cleaning path can cover a large area, cutting down the time it takes to vacuum. The Quiet Drive Poly-V belt eliminates the vibration associated with gear belt systems, thus reducing the amount of noise when the power head is running. There is a built in Dirt Sensor that will turn green when the area your vacuuming is clean. The Centec CT18DXQS is a direct replacement for the Nutone CT650. These two power heads are completely identical to each other. This power head also fits some Panasonic and Sears Kenmore canister vacuums. The 4 position height adjustment can adjust to a wide variety of surfaces with just a tap of your foot. The wedge shape and large rear wheels help negotiate around and under things that you could not vacuum with other canisters. There is a built in overload devise that will help protect the motor from jams. You