Use ProHitter Batting Aid with your Cooperstown Bat to improve your swing and gain power. Trusted and used by the Pros, this batting aid creates the correct grip technique to increase bat speed, power, and control. The ProHitter Grip Aid also prevents bone bruises and stinging when you are jammed with an inside pitch. Fits both right and left handed players and can be used with or without a batting glove. Area for thumb may stretch.