PRIME BATS: Made exclusively with MLB Grade wood? only 3% of Louisville Slugger?s wood meets this standard. The ink dot is the stamp of the highest quality wood bat. Only bats that meet the slope-of-grain requirement are approved for play in Major League Baseball. Every Louisville Slugger Prime bat has been meticulously graded to meet this standard.  All PRIME models have Exo Armor Premium Hardcoat that doubles the surface hardness/ Â