You've got enough discomfort to worry about on grueling runs up steep roads and trails without your socks giving you a hard time, which is why the Smartwool PhD Run Ultra Light Logo Crew Sock will be your new best friend on those high-mileage days. It's made with a super light wool blend that wicks moisture to keep your feet cool and dry as you work up a sweat, and features mesh ventilation zones to boost your breathability when you really start cranking. Smartwool's Indestructawool technology ensures that this sock will be hanging around through tons of miles, and a Four-Degree Elite Fit system keeps the sock in place while you run.