From the manufacturer

Men's UA Iso-Chill Launch Run Hat

Runners need more from their hats than just keeping the sun out of their eyes. These are also light, stretchy, and breathable, with a built-in, cool-to-the-touch sweatband. Every runner needs a couple of these.

• Ultra-light stretch woven fabric is durable & breathable
• Iso-Chill sweatband helps disperse body heat, making it feel cool to the touch
• Laser perforations for added ventilation where you need it
• Adjustable hook & loop closure
• Reflective logos