?The Pro Air Sleeveless Base Layer is designed for the hottest, most humid and intense days, sitting close to skin, the exceptionally lightweight 3D Mesh fabric quickly wicks sweat away from your body increasing breathability and keeping you cool. The 3D Pro Air fabric has a slight natural stretch meaning the jersey is always sitting close to skin, working hard to regulate your temperature, keeping you feeling dry and fresh, even on the longest of rides. Due to the incredibly lightweight nature of the fabric, sweat pulls away from your skin and exits fast so the base layer never gets weighed down.