Aluminum bats are an alternative to more traditional wooden bats. They are used in Little League, college baseball and some international events. Aluminum bats have never been used by Organized Baseball, Nippon Pro Baseball or the independent leagues. Summer collegiate leagues do not use aluminum bats as they try to help players get used to the wood bats they will use in their professional careers should they make it to Organized Baseball.
Aluminum bats were used at one point by Serie A1, Hoofdklasse and the Cuban National League, but all those leagues switched back to wood, resulting in separate record books for both eras. The reason for this is that aluminum bats significantly increase offensive levels as the ball travels further when hit by an aluminum bat. Some legislators have tried to ban aluminum bats in Little League due to possible higher rates of injury as a result of the increased velocity, but lobbyists for the industry and PR flacks like Ari Fleischer have fought such legislation.