The GoSports Plyometric Weighted Training Balls are an invaluable training aid for baseball and softball players of all skill levels. Introducing plyometric training into your practice routine will enhance player's strength, conditioning and range of motion resulting in better on-field performance. The PRO Set includes 6 Plyometric Weighted Balls ranging from 100-450 grams (100, 150, 200, 250, 350 & 450) providing for dynamic plyometric exercises for players of all ages and abilities. The durable balls are constructed from a soft, yet incredibly durable rubber shell that will last for countless seasons. The set includes a durable tote bag for easy storage.