These are tabi socks that you simply slip on like regular socks. I wore them once, washed them at home, and then stored them. They stretch well and are easy to wear. The actual measurement is about 15cm. They are stretchy, so I think children with sizes around that will be able to wear them. I have carefully checked them, but as I am a private seller, there may be oversights. I apologize if there are any. Please refrain from purchasing if you are looking for a perfect item.