Here is a larger style watch band for the T-Mobile SyncUp Kids Watch. Our son's wrist was just a bit larger than what the t-mobile syncup kids watch came with. So we've tried different bands without any luck and lots are about the same size. This band is large enough that even an adult male could wear it on the bottom few holes. It also goes small enough for a young teen to have years of growth with this band.

It's easy to swap over all the parts from the T-mobile watch to this new style of watch band. The latch part is a little tricky but not bad. I even put the little notch where the special release tabs come out of like the original band. You could run into a little issue trying to stretch the TPU over that latch. In the above photos I show this with some RED circles and arrows. You might have to clip that little spot to slide it in all the way. Not a bit deal and will still function fine. If you've had to replace these pins with after market ones don't worry about snipping that spot. Just slide it in and away you go. My son really likes this band a lot more and he can tell his friends it's 3D printed.