The Darn Tough 1/4 Ultra Light Cushion is an ultra comfortable, lightweight running sock which delivers cushioning just along the bottom of the foot. The sock pulls moisture away from the skin and repels bacteria and odor. It is made of merino wool which ensures breathability and comfort in all conditions. The sock sits just above the ankle and has an undetectable seam fusion which gives the ultra smooth invisible feel. 49% Merino Wool 48% Nylon 3% Lycra Spandex .