Constructed of a 3/4” Sturdy Steel Tube Frame, you will love these chairs. The seat and back are made with flexible polypropylene and attached with heavy-weight steel rivets strategically placed to provide durability and make them the most comfortable and ergonomic chairs on the market. The polypropylene seat and back are softened to avoid the brittleness that causes chair breakage in extreme cold and heat. All Metal Parts are Powder coated. When folded, our lightweight plastic folding chairs are easy to store and move. Our plastic metal folding chairs can be stacked over 85 chairs high.