The Tudor Collection Small Letter Plate Smooth Black Iron works well on rustic, wooden front doors. It measures at 265mm x 106mm and the aperture size is 205mm x 46mm. It is sold individually and comes complete with fixings. Smooth Black Iron Letter Plate 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.