Australian Merino wool: Men's mountaineering socks are made of 53% organic Merino wool, 25% nylon, 17% polyester and 5% spandex blended materials, which are durable and elastic. Merino wool materials are imported from Australia and New Zealand, where Merino sheep are raised. We use their natural wool to make clothes without harming Merino sheep. The wool comes back every six weeks.