Custom Underload Training BatCan be used to hit baseballs in tee work, front toss and regular batting practice. We offer them in 31" 35" Standard weight is approximately 8. The Underload Trainer is one half of the overload under load training platform to really help train and increase swing speed. The combination of using both and Overload and Underload trainers along with your game bat will help you take your game to the next level. Custom build your trainers just like you would