Jack-It Big League On Deck Weight - Adult Created by ball player for ball players, the Jack-It Big League On Deck Weight is a complete hitting system that provides immediate results by quickly building bat speed and power. Itís designed to be optimally positioned on your bat so you can warm up using correct swing mechanics. The cone-shaped, rubber coated carbon steel weight has an open side that slips onto the handle of the bat, so it fits snugly at the bottom of the barrel above the batterís hands. It forces your hands to work properly, thus creating improved technique, so you can step up to the plate with confidence. 21 oz.