"The Columbia Tech Trail Utility Polo builds Omni-SHADE UPF 50 sun protection into a 93% polyester, 7% elastane blend that stretches through a full range of motion. That stretch keeps the polo comfortable through a swing, a hike, or a long day of errands, while the sun protection works quietly in the background without adding any bulk. Vents at the side hem let the polo breathe when the temperature climbs. What Our Gearhead® Experts Are Saying:""I wear this on the hottest days because the Omni-WICK fabric keeps me dry long after a plain cotton polo would've soaked through, and the side vents move air the whole time I'm out."""