NIKE Pro Hypercool Sleeveless Vest 84% polyester Sleeveless - for excellent range of motion when hitting the gym or sprinting. Mesh panels - at side-seams with contrast stitching, for breathability and comfort when ru Mesh panels - at center back for additional breathability in high heat zones. Fabric - Body (front): Dri-FIT 84% polyester/16% spandex. Body (back): Dri-FIT 93% polyest Machine wash.