Highly cushioned for comfort and built for a long life, the Patagonia Heavyweight Merino Wool-Blend Knee Socks are engineered for warmth in cold conditions. They're made with Responsible Wool Standard (RWS) wool certified by Control Union (TE-00052557). Patagonia blends RWS wool with nylon and spandex for excellent stretch and recovery that lasts the lifetime of the socks. The purchase of RWS-certified products demonstrates demand for better animal welfare practices and responsible land management in the wool supply chain.