Herringbone weave fabric. Pre-curved peak. Metal ventilation eyelets. Rip-Strip™ size adjuster. Head circumference: 58cm. The... Herringbone weave fabric. Pre-curved peak. Metal ventilation eyelets. Rip-Strip™ size adjuster. Head circumference: 58cm. The visor is made from recycled polythene, which is a tough, light and flexible resin.