Little League Adopts USA Bat Standard. Starting in 2018, Coach Pitch, Minors, and Majors players are ONLY allowed to use a wood bat OR any 2 5/8" or smaller barrel bat that has the USA Baseball Certification Mark. Do not get confused by the USSSA certification mark. You do not want to get a bat that has the USSSA Certification Mark. These are not legal for Little League 2018.