It's a cap with a flap on the back of the cap. Otherwise known as, a legionnaires hat.
5 panel construction with a 6th panel on the back (in the form of a cap flap).
It's made of nylon so it dries quick and you can wear it in the ocean, and also the flap is quick-dry.
One size fits all (unless you have quite a large head, then it's a bit tight).. Also, if your neck is long, there should be enough flap to cover it.
They come in two colours, Sand or Navy. And they've got a little cottage logo (like the one at the top of the website...)