This is another great training aid for keeping the putter square through your stroke and on a good path while also making sure of a centre strike .You simply align it up with where you are aiming and keep the putter pressed against the arc through your whole stroke.You will find it very difficult to go wrong and it even has lines along the arc to help you gauge how far back to take the putter which will make your pace control consistent as well .The only downside is that while being really light