The CoolSwitch Trail Short-Sleeve boasts Under Armour's revolutionary CoolSwitch technology, which helps cool your body and skin so you can perform longer. This classic HeatGear t-shirt is body-mapped with mesh panels for increased breathability and comfort. ArmourBlock technology helps neutralize odor-causing microbes to keep you smelling fresh. Built-in UPF 50 sun protection shields your skin against harmful UV rays. Body: 90% polyester, 10% elastane fabric. Mesh Panels: 92% polyester, 8% elastane fabric. Loose fit. Imported.