UA CoolSwitch ArmourVent™ 2.0 Cap Hat New with tags Please make sure you review size chart 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. UA CoolSwitch uses an exclusive coating on the inside that pulls heat away from your skin, so you actually feel cooler delivers true breathability in a light, stretchy, durable, fast-drying fabric