Louisville Slugger XX Prime Birch Wood Bat. Hickory in color. Professional Louisville Slugger Bat. C243 Turning Model. The XX Prime is a step down from the MLB Prime Series from Louisville Slugger. This model features MLB Prime grade Birch wood that didn't make it to the MLB level. It has a pro cupped end and a large barrel. Birch is lighter in weight than maple so you can still have a large barrel bat with strong wood without sacrificing on quality.