Line M Up snaps onto your golf ball to allow you to easily and accurate add alignment and identification marks. There are many different marking options that allow for a variety of uses. Use your marks to align your shot or tell if your putt is rolling straight. Line M Up also works great to add unique identifiers to you ball. The Line M Up Pro Ball Marker enables you to mark your straight line to the pin to sink more putts. Includes a Sharpie to mark your ball. Conforms to USGA rules.