“Visual feedback is invaluable for helping golfers… Laser Putt’s dual independent adjustable laser system projects a red dot straight in front of the ball as an aiming tool and a green laser line to track the putter’s path… to help putters who manipulate the clubhead…”
http://www.golfdigeststix.com/golfdigeststix/20150909?sub_id=QdxaW6josiXA&pg=19#pg19