I have a smaller than average head and have always struggled to find a hat that fits properly. Between the smaller circumference options and the reduced crown height these are great! The return system is very easy to use and fast. HOWEVER: the 2 hats I have in small fit differently! The first is great, the 2nd seems to have a longer circumference so when I tighten the hat to fit it gets deformed in the back - one of the very problems I was hoping to get rid of. (I did try the XS size first as the circumference was more in my range, but the crown height was too short.)
TL;DR: Great hats for smaller heads, but very disappointed that sizing is NOT consistent.