Learn the proper form and basic bio-mechanics of baseball pitching and throwing. Throw-Rite is designed to show "fluid arm motion" and to give players instant feedback on the correct throwing motion. The two leather cover regulation baseballs are connected by a 2" nylon rope. When the arm moves properly through the arc of the delivery, the top ball travels without touching the thrower. When the player starts to "short arm" the ball, the top ball will flop over to hit the back of the hand. Instant feedback! Can be used for over-hand and side-arm delivery. Used from youth leagues to pro players. Drill sheet included. Patent pending.