What materials are the chairs on the market now?

What I know are: plastic, plastic wood, imitation wood, wrought iron and so on. There is another kind, which is popular in the north now, called steel-core environmental protection wood. It is widely used in the Bird's Nest in Beijing, the Water Cube and universities in the north. As above, all the chairs and legs are cast iron. If you are interested, you can have a look at this website, which is made of steel core and environmentally friendly wood. This is a patented product. Www.huanyang.com can also contact them if necessary: 995 124 103.