Brooks Infiniti 7310 Double Tab Sock, 1-Pair Pack Dri-Stitch Nylon 96% Dri-Stitch Nylon, 4% Lycra Technologically advanced performance fibers in impact areas to reduce irritations. Y Heel gore creates a deeper heel pocket, providing a better fit. A flat toe seam all but eliminates the chance of blisters caused by friction between harsh seams and toes Machine Washable, Tumble Dry on Low, non-chlorine bleach as needed USA