Layered under a jacket or worn on its own, the Nano Puff is one of the most thermally efficient insulated vests available. The smooth polyester shell has a DWR (durable water repellent) finish that lets you shake off water. The incredibly lightweight and highly compressed polyester insulation provides excellent warmth for its weight and stays warm when wet. Brick quilting pattern on side panels stabilizes the internal insulation and uses durable thread for abrasion resistance. Patagonia Women's Nano Puff Vest