You will want to sweat with the Zero Rules™ polo from Columbia. You are not dreaming, it will use your sweat to activate its Omni-Freeze ZERO™ cooling system and keep your body temperature constant. It is combined with Omni-Wick™ technology that wicks away your sweat and keeps you dry throughout the effort. Hiking or trail running has never been so enjoyable. This product features an antimicrobial treatment designed to protect it from bacterial growth. Omni-Freeze ZERO™ cooling system Omni-Wick™ Composition: Interlock Omni-Freeze ZERO™ 100% polyester Columbia Zero Rules Polo Shirt - Polo shirt - Men's