Polartec® Neoshell® is the world's most breathable waterproof fabric. Dynamic, two-way air exchange inside and out improves natural thermoregulation. It keeps you dry while providing the necessary protection from water and wind, blocking 99.9% of the wind. Water repellency is permanent and guaranteed over time because it is achieved through the mechanical construction of the fabric and not with surface coating treatments. Comfort is active because the fabric has four-way stretch.