The Tudor Collection Deep Casement Fastener Smooth Black Iron has a simple square design and is suitable for weather stripped windows. The length is 128mm and the projection is 41mm - it is sold individually and comes complete with mortice plate, hook plate and fixings. Smooth Black Iron Window Fastener 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.