Line-M-Up Pro                Ball Alignment Tool Line-M-Up snaps onto your ball and self-centers for straight and accurate markings. New alignment options allow you to mark your ball over 6 different ways!  Underside ridge prevents smearing of line markings. Concave marker slot allows easy marker tip access. Supplied with a matching Sharpie Mini (ball not included). Used as a playing or training aid by giving you a visual guide to help line up all your shots.  Conforms to USGA rules and is legal to use in competition. Line up putts - Professional golfers line up their putts, so that they can concentrate on length. Line up tee shots - For more accurate tee shots, use the line to point you in the right direction. Practice putting - When a good stroke is made, the line on the ball will roll straight; struck poorly, the line will appear to wobble as it rolls. Identify your ball - Under the rules of golf, you are required to identify your ball with a mark.