The beauty of this cap is that it folds flat - bill and all - so it can go in your hip pocket, purse, backpack, or whatever, without crushing it. It's made of 97% polyester and 3% cotton, in a tight weave to prevent the sun shining through. This would make for a 'hot hat', except that there is a web panel on each side for breathing. The adjustment in the back has a plastic snap device that holds securely.This cap isn't 'structured', meaning it has no stiffener to hold its shape, and that's what See full review