The Original US Patent Pitchers Power Drive. Developed by professional trainers at the Winning Pitchers Academy in Boston. In 4 years the PPD is already used by 24 Professional and over 400 college teams. Many MLB pitchers personally own a PPD and are using to improve their performance at the highest level. Built to last a players and coaches" career. Operates on a pitchers natural gravitational force just like in a game...NO SPRINGS to resist or assist their real game pitch delivery. Free access to the "Owners Only" web base training site included with each PPD. 100% made in the USA.