The Smartwool PhD Run Ultra Light Micro Running Sock gets you through extensive miles in comfort. Whether you're running a long race or are spending a season getting in shape, the Indestructawool and Shred Shield technologies deliver durability and reduce wear and tear for sock longevity. Mesh ventilation zones provide moisture management and breathability for runs on warm afternoons while the merino fibers repel unwanted odors to keep you fresh through the miles.