Terramar 1.0 Trailhead CS Lightweight Long Sleeve Crew Shirt- Men's 100% Polyester ClimaSense Thermoregulation Technology keeps you comfortable in all conditions - Engineered to adjust to your body temperature - Inhibits the growth of bacteria that causes odor - Fast wicking and drying Digital air pockets enhance moisture management and breathability Lightweight warmth (1.0) makes Trailhead extremely versatile Flat seam construction UPF Rating 25+