The Hitting Jack-It is the games first variable weighted hitting system that allows you to hit live batting practice. The product comes in three primary sizes to assist progressive training. The 9oz size develops bat speed and works fast twitch muscles. The 12oz size strengths hands and forearms, and improves muscle memory. The 16oz size develops power main package is for the three units only 9oz-12oz-16oz.The product works with all Baseball and softball bats allowing players to develop during live batting practice sessions and off hitting tees. All current weighted products on the market are placed on the barrel of the bat causing a casting elongated swing, slowing down your swing causing less power and do not let you practice with live pitching. The Hitting Jack-It was developed as a complete hitting system by ball players for ball players to provide immediate results, quickly develop bat speed and power, and force your hands to work properly creating improved technique. The Hitting Jack-It training system provides multiple benefits immediate results easy to use can hit live batting practice quickly develops bat speed and power keeps your hands from casting gives you more confidence as a hitter available in three main graduating sizes: 9oz, 12oz, 16oz available for softball players Forces hands to work properly creating a shorter compact swing strengthens hands and forearms can also be used as a weight for on deck .