This year for baseball we have moved from Pony Baseball to Centex Series.  Below are the bat rules with Centex.  

The official bat shall be round in cross-section for its entire length, straight from end to end for its entire length and smooth surfaced in the hitting area. It is the manager’s responsibility to ensure compliance with this rule. 

1) For ages 8 and under- The maximum diameter shall not exceed two and five eighths (2-5/8”) inches. All bats larger in diameter than two and one quarter (2 ¼) inches must be "equal to or heavier" than minus 10 (- 10) for U5 thru U8. For example: -10, -9, -8, -7, -6 or -5 are acceptable length to weight ratio’s whereas -11, - 12 and -13 would not. 

2) For ages 9 and older- The maximum diameter shall not exceed two and three quarters (2 ¾”) inches. All bats larger in diameter than two and one quarter (2 ¼) must be labeled with either a BBCOR or 1.15BPF stamp. 

3) The maximum bat length shall not exceed thirty-six (36) inches. The bat shall be constructed of wood, aluminum, or any other material or combination of materials. Any material to improve the grip may be used for a distance not to exceed eighteen (18) inches from the handle end. All bats must be commercially manufactured for baseball play, softball bats or bats altered after manufacture to reduce or add weight will not be allowed. Penalties – Use of an illegal bat shall not be grounds for ejecting the player or declaring the batter ‘out’ except as follows: A) If the umpire discovers that a bat does not conform to the Centex bat rule stated above before a ball has been put in play, the umpire will remove the illegal bat from the game and issue a warning to the manager. Warnings will be recorded on the game card. B) If the umpire discovers that the bat does not conform to the Centex bat rule stated above after the ball has been put in play and before the next legal pitch, the defensive team will have the choice of the result of the play or the batter being called ‘out’. If the batter is declared ‘out’, all runners must return to the base officially occupied before the pitch. C) A second offense incurred during the Centex series will result in the manager being ejected in addition to application of the first offense penalty.