Under Armour Iso-chill Breathe Adjustable Women's Cap 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. Using amazing technologies, Under Armour have provided you with the perfect running cap. Iso-Chill is an Under Armour technique that allows you to stay cool and calm during your intense sessions. The Iso-Chill sweatband is what helps the dispersion of body heat, ensuring that it's cool to stuff, for a better experience. Using ultra-light woven fabric, this hat is both durable and breathable, making for a more comfortable experience. Laser perforations in the hat are strategically designed to keep your head feeling cool and ventilated, ensuring comfortable wear whilst keeping the head protected from the sun. Under Armour know that hair getting in the way can ruin your running experience, which is why they have provided a large back opening on the ha