Markwort Learning Curve Baseball Develops pitching and hitting Skills. Durable rubber construction makes ball easy to grip while teaching proper finger placement and hand motion to throw a curve ball. Increases the curve rate to provide pitchers with greater visual feedback to help improve the learning process. Provides true pitching motion and visible ball rotation to help batters improve their curve ball hitting skills. Attractive clamshell packaging allows gripping and feeling the balls construction. Easy to follow instructions on back of the package. Recommended for use with pitchers ages 12 & up and for training batters of all ages. Patent Pending.