Shell in plastic composition with up to 25% wood fibers. The sled base is made of Powder coated steel. The wood fiber and plastic mixture is injected into the mold and forms the shell of the chair. Swivel piece is cast aluminum. Swivel base is molded in one piece. Clean with a damp cloth. If necessary, use a little detergent on the cloth. For upholstery versions, see cleaning instructions for your chosen square fabric. com or for leather at ca-mo.com. For versions of leather upholstery: Clean the leather regularly with a dry cloth. Treat the leather at least four times a year by using only special leather treatment products for aniline leather.