41% Alpaca, 34% Acrylic 23% Nylon, 2% Spandex. Unisex sizing: Size Large – fits a 10-13 shoe in Women's and a 9-12 shoe in Men's. Alpaca is incredibly soft and twice as warm as wool. Alpaca wicks away moisture and is less allergenic than wool. Designed in the U.S and fairly produced in Peru. Machine was cold water, tumble dry low. Some shedding will occur during wash/dry cycle. This is a jacquard knit sock, to create that beautiful design there are threads on the inside.