The Darn Tough Her Spur Boot Sock features Merino Wool that keeps your feet dry, while the silky, light cushion adds miles to your hiking journey. The naturally antimicrobial sock is an all-weather performance sock. It is made of 54% Merino Wool, 43% Nylon and 3% Lycra® Spandex. The sock features a performance fit, fine gauge knitting, fast action wicking and True Seamless™ for an ultra smooth, invisible feel. All Darn Tough socks are Still Made in Vermont, USA and carry a lifetime guarantee.