HexDelta intelligent technology adapts to any activity for non-stop comfort & versatility. Ergonomic flatlock seams allow you to move free without fear of chafing. Shaped hem delivers enhanced coverage without looking big & bulky. Cutout keyhole in back for extra ventilation. Mesh panels for extra breathability. Free cut extension on sleeves fit securely & feel super-smooth. Reflective details deliver greater visibility on low-light runs.