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.