Thinnest single layer sock that provides a second-skin feel. The perfect sock for all aerobic activities and great for racing and x-country flats. - Repreve® Polyester performance fibers keep the foot cool and dry - Seam Free Toe for added comfort - Y Heel promotes an anatomically correct fit - Favorite socks for the minimalists Fiber Content 68% Repreve® Polyester, 44% Nylon, 8% Lycra®