Breathable Mesh: the mesh side panels allow ventilation which makes your head breathable in sunny with strong sunshine. Material:Polyester. Light Wearing. Made of quality polyester which is lightweight, quick-drying, foldable, water and stain resistant. Perfect for Outdoor Activities and Sports.Walking, hiking, fishing, playing golf, gardening, sightseeing, on the beach, at a ball game BBQ or working outdoors. One size fits 21.6-23.2. Could adjustable Fit. A fused hard buckrum sewn into the front of the crown provides excellent structure and helps maintain the original flexfit shape. The function of the foldable hat is more convenient to carry.