As a playing aid the Line-M-Up conforms to USGA rules and is legal in competition to help you align your putts and tee shots to improve your score.

As a training aid the Line-M-Up gives you a visual guide when putting.  When a good stroke is made, the line on the ball appears straight as it rolls.  When poorly struck, the line will appear to wobble.  When a Pure Stroke (no wobble) with the proper speed misses the hole, you can identify a missed read to improve your green reading skills.