A proprietary waterproof and breathable technology from The North Face, HyVent® membranes are used on the majority of both their kids and adult outdoor garments. This fabric has a multi-layer, polyurethane coating that is not only extremely waterproof, but also moisture and vapor permeable, allowing excess heat and moisture to be expelled through the outer layer of the jacket. The PU coating on this material also makes it quite durable. All of these qualities are incorporated in such a way that the garment maintains them throughout its life.