Hmm... Seems like he used a 19 oz. bat at that age, but I do remember some teammates who had 16s. If I remember correctly, one way to make sure it's not to heavy is to have him hold the bat by the handle with one arm, and extend the arm with the bat pointed straight out (horizontal to the ground). If he can do this comfortably, then the weight is OK. If he's shaky, go lighter. My son's favorite bat in those days was a -9 Worth Insanity.