Under Armour Men's Ua Iso-Chill Flats Guide L/S Shirt Part of the HYDRO ARMOUR collection Iso-Chill fabric helps disperse body heat, making it feel cool to the touch ArmourVent mesh underarm panels deliver true breathability in a light, stretchy, durable, fast-drying fabric 30+ UPF protects you from the sun's harmful rays Stain release materials keep blood, guts & dirt from soaking in