The Chill-Its 8935MF Hi-Vis Sun Hat is a lightweight and breathable sun protection hat with advanced microfiber cooling technology lining the rim for relief in extreme heat. This 150D polyester sun hat is rated to UPF 50+ and features a wide brim for complete face and head coverage, while 360-degree mesh venting maximizes airflow for breathable comfort. The hi-vis colors and 1in // 2.5cm reflective tape are ANSI 107-approved to keep workers safe and seen. Evaporative cooling technologies such as microfiber are a simple, effective and comfortable solution for heat stress prevention. Evaporative technologies use an external water source to draw heat away helping to regulate body temperature while providing cool relief. HOW TO ACTIVATE Run the inside rim of the sun hat under water for one minute to activate instant cooling relief that lasts up to three hours. The ultra-absorbent microfiber will retain water while remaining soft and comfortable.