The Tudor Collection 308mm (12\") Casement Stay Smooth Black Iron has a simple square design meaning that it will work well in a variety of settings throughout the home. The size is 308mm (12\") and is sold individually, complete with fixings. Smooth Black Iron Window Stay 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.