With the Putting Plane Alignment System you can easily use the mirrored surface to check if your eyes are over the ball, shoulders are lined up, and the putter face is square. Its adjustable rails enable you to practice a perfect back and through stroke that is on one plane. The angled rail, adjustable to fit any putter and slanted at 72 degrees, allows the putter to come slightly inside as it moves back and up during the stroke. You will have never rolled it so smoothly!