Lightweight performance fitting sock with cushioning underfoot for comfort. All the warmth of a midweight sock with 50% less bulk. Lightweight. Graduated compression for calf comfort. Mapped toe and forefoot cushioning for warmth. Shin pad shape improves boot tongue comfort. Best for Performance fit and warmth. 40% Merino wool, 39% Endurofil , 19% nylon, 2% Lycra . Machine wash warm.