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 minimalistsFiber Content68% Repreve® Polyester, 44% Nylon, 8% Lycra®