OTTO Solid Polyester 5 Panel Foam Front Mesh Back Cap - Grey 100% Polyester Made of 100% polyester, 100% nylon. ONE SIZE fits most with adjustable plastic snap closure, fitting up to XL size. Crown measures 3 1/2 inches deep, structured, 5 panels, high profile, 4 panels in mesh back. Bill measures 3 inches long, pre curved, same color under bill. Thick, stiff, soft and light material.