ExOfficio Men's Trip'R Stripe Short Sleeve Shirt 100% Nylon UPF 30 sun protection installed into the shirt guarantees protection of your skin against harmful UV rays. The zipper security chest pocket keeps all your small, valuable items safe and secure in a conveniently accessible location. With the combination of back yoke ventilation and side hem vents, you can ensure complete air circulation for a cooler breezier feel. Moisture-wicking technology eliminates annoying sweat build-up for a cleaner feel and dryer appearance, even on especially warm days.