The Polywood Shell Ottoman for Shell back Adirondack chair is made of Polywood recycled plastic. Recycled Plastic Polywood Lumber is made from over 90% post consumer plastic and High Density Polyethylene which is impervious to all types of weather conditions including rain, snow, salt water, sun and ice. Polywood has color fastness and UV inhibitors to reduce fading. Polywood never splinters, warps or corrodes and is tougher and more resilient than treated wood. Shipped knocked down, with easy assembly required.