Here's why:
"The Putting Impact System is built on the simple ability of every human. Our hand-eye coordination makes it easy for us to put a flat object on a flat surface... like when you clap your hands!.

If the ball had a flat side, it would be easy to hit it squarely with the putter face.

I created the Putting Impact System to help you visualize a 'flat' ball, and to put the putter face on the flat spot."

Hank Haney's Essentials of the Swing Book - Overview:

In this book, Haney goes beyond tips and quick fixes to lay out the principles behind the perfect swing. Point by point, chapters cover every aspect of the swing, from grip to contact to ball flight, with 160 illustrations to help players understand the concepts and check their form.

Putting Haney's approach into practice enables players to make the powerful, repeating swing that can hit every kind and shape of shot--with every club in the bag--with equal ease on a consistent basis. A master work from a master instructor, Essentials of the Swing will be essential reading for any golfer who is looking to reach the height of his or her game.