Rooster Polypro™ is constructed from a combination of Polypropylene (94%) and Elastane (6%). We've brushed the inner fabric surface to give it a thick, fleece-like, high quality texture which feels incredibly warm and soft next to your skin. The resulting garments provides excellent thermal qualities making it the perfect base layer. Polypropylene is naturally hydrophobic, which means the fabric feels remarkably dry, even when wet. We love wearing these socks underneath our Hot Socks which combine to create a fantastic heat barrier without adding bulk to the foot - in fact the possibilities are endless - our Polypro™base layers would be great under your ski suit, drysuit, winter cycling, kayaking, walking and anytime you need a thermal base layer.