I wouldn't rush into a 31. DD had a 30 through her first year of 12U and only went to a 31 to get the Slapper when Demarini brought it out. She used it up until this summer when she moved to a 32 in 16U. Mine is 5'3" about 125lbs and could swing a bigger bat strength wise but the 32" is her optimum size.I am looking for advice on bats. My daughter is turning 12 and currently swings a Vendetta 30/18. Bat size-wise, she is about ready for a 31". Debating on getting her a new bat. She got to test out several -11 bats and her swing speed and exit speed really decreased. Is this just due to the additional 2 ounces that she isn't used to yet? she needs to keep her speed higher. Would it be better to look into a 31" -12 instead of -11? Or, at what point does she truly need a longer bat? When doing the arm measurement, the 30" is just a bit shorter than her finger tips, maybe an inch. The guy at the store recommended -11's since she'd be "getting to an age when she needs to swing a -10". She is excited for a new bat but just don't want to spend money on one that isn't going to improve her hitting due to a slower swing.