This one of a kind tool was designed to overcome the frequent woodworking problem of keeping your scribe at a constant distance from the profile or surface you want to copy. Sure, it is easy to do when everything is flat or at right angles, but what about when you are trying to fit your piece against a contour of any kind? The Perfect Butt solves that problem. It comes with three different sizes of interchangeable tracing wheels which hold your pencil stable at its center and follow along almost any surface, keeping it at a constant distance from the profile you are copying and ensuring an accurate copy every time. Your pencil is also spring loaded so that it will remain in constant contact with your work piece whether it is flat or upright.