Our Adirondack chairs are made of HIPS, ranking of impact strength is HIPS--HDPE--PS--WOOD, we choose higher-level HIPS of impact toughness is 0.15 N/M, very rigidity, it can make your outdoor chairs durable and sturdy, HIPS is made of plastic and rubber, so it's not as brittle as HDPE, Once formed, HIPS has 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.