The sizing is odd - I ordered a 3-9 month (in cherry pattern) and a 5-6 year old hat. The brim and crown of 5-6y hat was not much bigger when lined up against the 3-9m and so unsurprisingly didn’t fit my almost 6 year old. I sent it back and got the 7-10 which does fit, not sure it would fit a 10 year old though, What I like - the sun protection, nice wide brim and the fabric is presumably the sun safe stuff as it is the same as the suits, although the description doesn’t say so. What I don’t like - there is no chin strap of way of securing the hat and for an active child who’s jumping about it doesn’t stay on, especially if windy.
