Brought these for my 9 yr old who is slim and 135cm tall. They fit fine, if your child is larger you might wish to size up. She's worn them weekly for ballet lessons for several months and they wash and dry well, no ladders.
I have started using Amazon to order ballet products as my previous supplier was always out of stock in the sizes I need. As with all the ballet tights I buy however, they don't last long without getting ladders/holes.