Pro Natura is the premier bamboo sock yarn available today. Zitron has blended the high quality wool that makes their regular Trekking XL yarn so popular with actual fiber strands of bamboo, resulting in gorgeous heathery colors and incredibly strong sock yarn. Also, unlike most bamboo based yarns, which usually use bamboo pulp, Trekking Pro Natura uses fiber strands of bamboo and retains bamboo’s natural anti-microbial properties, making it the perfect yarn for socks!