Sherpa’s PCD II Polypropylene has the lowest thermal conductivity of any traditional fabric, allowing your body to retain its natural heat. It does not absorb moisture, so it keeps you dry. Any moisture that is generated is wicked away from the body, leaving a warm layer of air next to the skin. PCD II Polypropylene is also very lightweight and extremely quick to dry, making it easy to keep fresh for multi-day users. It is significantly softer than other polypropylenes and is extremely comfortable to wear. You will always perform at your best in Sherpa PCD II Polypropylene Thermals!