Durable and strong meet soft and warm. Anatomical flex fit system provides a more perfect fit. Reinforced heel and toe. Merino wool combined with stretch nylon/lycra. Like your shoes, these socks come as a right and left pair. Material: Merino Wool 40%, Nylon 31%, Acrylic 14%, Polyester 10%, Cotton 3%, Lycra ® Spandex 2% small fits women's size 4-6, medium fits size 6-10 and large fits size 10-12.