The Tudor Collection 203mm (8\") Door Bolt Smooth Black Iron is ideal for adding extra security to your home. The size is 203mm (8\") and it is sold individually, complete with plates & fixings. Smooth Black Iron Door Bolt The smooth black iron finish does not have deep surface indentations like many other black finishes - this gives it a more modern feel. It is made from malleable cast iron, treated with a zinc phosphating process and then powder coated to provide a durable finish.