Invented by Steve Trout. Recommended by Hall of Fame Pitcher Greg Maddux, Four-Time All Star MLB Pitcher and Pitching Coach Tim Hudson and former New York Yankee’s Director of Pitching Coaches Billy Connors. When you order the system, it includes the plates as well as the direction of how to use the plates in a booklet named '20 Tips of Pitching.' Booklet is authored by various major league pitching coaches.