T-ball is the introduction for children ages 4 and up to either baseball or softball. This sport uses a stand that holds the ball instead of someone throwing the ball at them. Even though this game is not played at a professional level, they do have rules regarding the size and specifications of the ball equipment.
Ball – 9″ to 9½” around; 4 to 5 ounces. Softer than a standard baseball. Molded core or sponge rubber center.
Rule 12 of the Official T-Ball Rules – Each team must furnish one (1) new baseball per game. The baseball MUST be an official T-Ball baseball. This game ball will be given to the umpire before the game starts and will be returned after the game.
T-ball USA Rules – http://www.teeballusa.org/rules.asp
Official T-Ball Rules – http://www.rcwll.org/OFFICIAL%20T-BALL%20RULES.pdf