Markwort Throw-Rite Pitcher?s Training Device Can be used for over-hand and side-arm delivery. Used from youth leagues to pro players. Great for any player at any level: beginners that are starting out and learning the basics of throwing motion, and advanced players that are trying to perfect their skills until they become routine. When you throw and the ball hits you in the hand, it means that you are not using the proper arm arch and that your entire body is not being used properly. Drill sheet included.