The Rab Women's Sonic Ultra Tee is an athletic short-sleeve shirt specialized for running on sunny mountain days. Its Dryflo Air material is Rab's lightest, most breathable fabric offering moisture-wicking, quick-drying comfort. Laser-cut ventilation amplifies airiness in key areas, and while the fit is slim, the seam-free sleeves help prevent chafing. It's also easy to layer up when you reach higher altitudes.