Ex Officio designed its Men's Sol Cool T Shirt to keep you cool in any hot weather activity under the sun. A combination of polyester and spandex gives you the comfortable stretch you need whether you're backpacking, hiking, climbing, cycling, mountain biking, or running. Ice Fil technology containing xylitol derived from birch trees wicks moisture and keeps you at a solid five degrees cooler than the air around you. Ice Fil technology also gives this shirt antimicrobial properties, meaning it won't stink as badly as you do after a difficult hike under the sun. Its natural fit includes raglan sleeves and an underarm gusset to give you the mobility you need to climb comfortably. Flatlock seams add comfort when you're backpacking with a heavy load on your shoulders.