Lightweight - Built light, darn comfy and super strong—substantial construction for a lightweight, sure fit. True Seamless technology allows for an undetectable seam fusion for an ultra-smooth, invisible feel. Over-The-Calf-Height - The name says it all. The ultimate height for keeping the outside—out. Composition - Knit with 61% Merino Wool, 37% Nylon, 2% Lycra Spandex. The fast action wicking pulls moisture away from skin, so no more sweaty, stinky socks. The soft, breathable merino wool has fast drying, all weather performance that keeps you cool in the summer and warm in the winter. Guaranteed for Life - If these socks wear, tear, or develop holes, Darn Tough will replace them. No strings. No conditions. Made in the USA with yarns from America and around the globe - Every pair of socks is knit in Vermont - the perfect testing ground for the finest premium all weather performance socks.