Description of SmartWool PhD Cycling Ultra Light Mini Socks Looking for a cycling sock that won't give out just because it's winter? Featuring our new SmartFit system, our new PhD Cycling Ultra Light minicrew offers skin tight performance and new micro loop cushioning in the high density impact zones for added durabilty. This is an ideal cycling sock for year round performance. Features: 56% wool, 40% nylon, 4% elastic