Our Adirondack chair with ottoman is made of HIPS, ranking of impact strength is hips HDP eps wood, we choose higher-level hips of impact toughness is 0.15 n/m, very rigidity, it can let your outdoor Adirondack ottoman durable and sturdy, hips made of plastic and rubber, so it's not as brittle as HDPE, once formed, hips have good stability and abrasion resistant, it will not like wooden chair warp, peel, cracking or rotten, realistic wood grain surface design, look and feel like real wood.