Champro Leather Weighted Training Softballs Description: - Leather Cover - Stripe pattern allows monitoring of pitch rotation Available in 9oz, 10oz, 11oz and 12oz. The Concept: Conditioning with weighted balls ahas been referred to as Overload Training. Many players agree that training with weighted balls can improve dtheir velocity when playing with a regulation game ball. As with other types of weight training, a player can gradually increase the strength of his or her arm by training with progressively heavier balls. Size: 12 Warning: Weighted training balls are intended to be used with caution in a supervised muscle development program. As with any physical activity, injuries may occur. Even when used properly, there is a certain degree of risk. Weighted balls should not be hit with a bat or thrown to another player. They should only be thrown into screens or used for stretching exercises. The manufacturer can assume no responsibility for injuries resulting from the use of weighted training balls.