One set includes two oversized plastic Adirondack chairs oversize Adirondack chairs bring boxy lines to your outdoor or living space. It is made of solid HIPS composite material, not plastic in the traditional sense, which is a proprietary material. The great thing about opting for Adirondack chairs made from composite plastic material is that they are incredibly durable and require little to no maintenance. Whether you're lucky enough to have a backyard or are trying to make the most of a tiny rooftop terrace or concrete patio, an Adirondack chair is a classic choice for kicking back with a book or a glass of wine.