When working with the Contour SCT, sometimes there is just not enough room to get the 4 inch wide drum close into the corners of what you are working on. With the Contour SCT Narrow Face Wheel System, you now have the ability to get deep into corners or odd body curves to complete your project. Simply choose what position you want the wheel to be placed (Left, Middle or Right) by installing the Aluminum spacers and the wheel in the correct order .