The T3 All Season Trekker Features 3 separate layers of fibers that work together for comfort, support, and moisture management. A layer of TENCEL® provides a layer that is soft to the touch and comfortable against the skin. It is a fully biodegradable fiber that is made from trees from sustainable farms. The COOLMAX® layer works to move perspiration away from the body, and through the fabric, where it can evaporate quickly, allowing the wearer to feel cooler and more comfortable. Lastly, a layer of Nylon and Ea. LYCRA® adds durability and ensure these socks stay up in your running shoes without slipping down to your toes. This is a fantastic sock for hikers looking for moisture management in mid-warm temperatures.