What he ^^^ said. I opted for the shorter version.
If shes moving up to 12s and shes 5'1 get the taller tee... I lost my tall Tanner and ended up buying the short one as I have midgets for kids and have one in 8U still but my 12U and 14U will not be able to use the short tanner for high pitches... it depends what your kid struggles with more... mine had more problems with low pitches so the short one worked better and is more usable by the 8U crew