I'm a size 1-3 (the tights say "S") and they fit my 21 month old perfectly. It's still a little loose, but I just keep it on top and she can still use it when she's grown a little. We simply need tights because the baby cannot wear socks.
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Pros
They are great to wear under dresses in winter and spring.
Cons
The color is not the same as the picture, there is no pink, why put on the photo