Line M Up Precision Ball Alignment Tool The Line M Up Precision Ball Alignment Tool by Green Keepers is the #1 ball lining tool in golf. Line M Up allows you to easily identify the center of your ball, making it easier to improve your aim and green reading abilities. Line M Up also makes a great golf ball identifier by adding personalized marks to your ball. Sharpie and bonus 4 Yards More tee included. Conforms to USGA rules Features: Sink more putts, hit more fairways, and save strokes Improves