This hat was designed to keep your head cool by dumping excess heat through special vents that allow hot air out, but are small enough that the sun's rays aren't an issue. ArmourVent™ Technology delivers ultimate breathability in a light, stretchy, durable & fast-drying fabric. wicks sweat & dries really fast. Iso-Chill sweatband & front panel lining helps disperse body heat, making it feel cool to the touch. Adjustable back closure. UA Free Fit: pre-curved visor & unstructured front conforms to your head for a sleek, low profile fit. 54% Nylon/31% Polyester/15% Elastane.