Topex Mens UPF50 Quick-Dry Baseball Cap Foldable Brim Free-Size Sun Hat Unisex Quick-dry fabric:100% nylon. FREE SIZE: with an adjustable velcro strap in the back, one size fits most. WELL VENTILATED:the mesh design make it feel so breathable and lightweight in summer outdoors. PACKABLE:could be packed easily into a bag or even pocket. 3.2" BILL: brim is firm and of adequate length to provide shade from sun light. SPF: passed UPF 50+ test, could block most sun UV rays.