When it's cool enough to rock long sleeves but not so cool that you won't burn up running in a fleece, turn to the just-right comfort of the Under Armour Vanish Seamless 1/2-Zip Shirt. As the name suggests, you'll hardly notice you're wearing this shirt as it wicks moisture and keeps you cool during workouts. Versatile enough to use in a range of weather conditions, it finds its niche as a layer or standalone piece during high-output, cool-weather runs. The super-light fabric boasts excellent wicking quality, and won't chafe or cling to you while you run, ensuring comfort during uncomfortable pursuits. The body-mapping mesh ventilation delivers breathable performance throughout almost the entire body, with regular wicking fabric in the stomach and chest where you may not need as much airflow. And when you find yourself heating up from intense exertion, the deep chest zipper provides easy and effective temperature regulation.