http://www.intheholegolf.com/PLNSIGHT/Plane-Sight-Golf-Laser-Trainer.html
Plane Sight is an innovative golf training aid. One of the keys of every golf swing is the swing plane. The swing plane can be thought of as an imaginary piece of glass extending from the ball over the golfers shoulders. It is shown in blue in the photo to the right. A golf swing that is on plane will follow a path parallel to this imaginary piece of glass as shown in red. While this is not hard to understand, it is very difficult to visualize. Trying to see or feel where the club is during your backswing without stopping or looking up is nearly impossible. Some have tried large circles of PVC pipe to swing over. This works well but is not very practical. It is large, expensive and not very portable not to mention what it does to those graphite shafts!
Learn more about the Plane Sight Laser Golf Swing Trainer at InTheHoleGolf.com:
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