With up to 400 ribs, the Sidewinder is one of nature's most flexible creatures. Sure, it's a snake. But it's a snake so flexible, it can even move sideways. Our new Sidewinder Shirt with DuluthFlex® technology gives you that same kind of agility and ease. You can move effortlessly all day, thanks to 86% nylon/14% spandex blend, underarm gussets and a box pleat. Like its namesake, this shirt is built for searing climates: super-light, 3.2-oz. wicking performance fabric has UPF 30, wicks sweat, keeps you cool. There's even breathable mesh under the back cape. So don't get rattled by summer heat or binding shirts. Bite back! With the Sidewinder.