The product basically allows you to stay square through the impact of your swing (you have to try to get both LEDs merging right around impact).
Also, you can check the path of your swing since the high output LEDs leave a trace while you swing. This is great for your home when you are not on the golf course.
And it can really help beginners to get their swing on square and hit the ball straight…
When the blue line is clearly outside the red line, your clubface is “open” at impact.
This will cause your ball to spin right. Notice that I am also swinging outside-in,
which will probably make my ball slice about 50 yards to the right of my target…
Likewise, when the red line is outside the blue line, your clubface is “closed at impact.
This swing shows that the clubface closed way before impact, which will
cause the ball to spin left and ultimately a big 50 yard hook.
For HOWTO, click here.