49% Olefin/48% Nylon/3% Spandex. NB DRY moisture management technology quickly moves sweat to keep feet cool and dry. Seamless toe to reduce abrasion and mesh panels to promote airflow. Anatomical left/right foot design for the ultimate fit. Strategic cushioning around heel and toe helps with shock absorption. Reinforced heel and toe for added durability. Knit-in size indicator.