Otto Caps Solid Cotton Twill Low Profile Nylon Mesh Back Cap - Khaki 100% Polyester Made of 35% cotton and 65% polyester. ONE SIZE fits most with adjustable plastic snap closure, fitting up to 7 1/2 size. Crown measures 3 1/2 inches deep, structured, 6 panels, low profile, 4 panels in mesh back. Bill measures 3 inches long, pre curved, same color under bill. Thick, stiff and light material.