100% polyester 3.5 ounce Milliflex with 92% polyester/ 8% spandex 8.5 ounce Dryflex contrast collar tipping, and uniquely shaped tapered contrast panels down the side and under the arm. A silky-soft, lightweight 4x4 stretch material that is long-lasting and easy to care for. With contrast stretch-nylon flatlock seaming to reduce chafing, and promote mobility and a better fit, this Hybrid item with a left arm zip pocket for your mp3 player is designed to move.