Our favorite thing about bamboo plants is that they are one of the fastest growing plants on earth, making it a good eco-friendly option.The FSC® approves our rayon fabric for being sourced from responsibly managed forests. FEATURES Accredited by the Forest Stewardship Council® for being sourced from responsibly managed forests Certified by OEKO-TEX® Standard 100 for zero harmful substances present  Made using rayon from bamboo for a super-soft sock Seamless toe which limits irritation or chafing Blended with nylon for durability and spandex for flexibility  Moisture wicking and great for sweaty feet Kind to sensitive skin FIBER CONTENT 78% Rayon From Bamboo, 20% Nylon, 2% Spandex SIZE DETAILS L/XL 10-13 (Women's Shoe Size 10.5+ and Men's Shoe Size 9-13) King Size 13-16 (Men's Shoe Size 12-15) CARE INSTRUCTIONS Machine wash cold. Do not bleach. Tumble dry low or hang to dry.