The SUN BLADE^™ Hat is designed for high heat and steady movement. A single-layer construction delivers maximum breathability and quick-drying comfort, while ICEKÜHL^™ cooling technology helps reduce skin temperature. A streamlined fit, adjustable chinstrap with cord lock, and flexible floating brim keep it light, packable, and easy to wear when the sun is relentless.SizingSmall circumference is 54 cmMedium circumference is 57 cmLarge circumference is 60 cm