Nike Mens DF Miler Long Sleeve NFS Running Shirt The soft fabric has Dri-FIT Technology that helps keep you dry and comfortable by pulling sweat away from your skin to the fabric's surface, where it quickly evaporates. Mesh panels on the sides and the entire back let body heat escape. This allows you to cool down as your run heats up. Thumbholes on the cuffs help keep the sleeves from flapping as you move. And, the top's seams are flat for a smooth feel as you run, no matter how many miles you put in. Slightly longer back hem helps prevent ride up Reflective elements help you stand out from the crowd - 100% Polyester