Thanks for the link!
I didn’t see anywhere what size heads so I’m going to presume (from experience) that they won’t fit me. I have never found a one size fits most hat that fits me.
(Not sure it is a style I would wear actually - may have to make one to find out)
They are all adjustable. My husband has a very small head and I have a larger head…
Some have velcro, some a bungee cord and some a strap like mine.
If I were to decide to try one, I’d contact them for precise size range. I’ve encountered adjustable hats that still are too small and some that just barely make it.
I do think they run a tad small…but you can use any cloth hat…I am thinking of getting some bucket hats to embroider! They are popular now and can be found just about anywhere…and you can try before you buy!
That sounds like another great project!!
I’ll have to look around and see what I can find. I’d much rather be able to try on before I buy! 
This is so absolutely amazing! I love the color bursts on the brown base. Gorgeous!