This Doorbell Ringer is cast in solid bronze. The oiled bronze finish is attained by successively dipping raw bronze castings into a patina solution and then buffing them to a satin finish. With the repetition of this process Michael creates the rich, dark multi-tone finish of his Oiled Bronze. The sand mold in our casting process can only be used once making each Doorbell Ringer truly unique. All Michael Healy Products are coated with a protective finish and carry Michael's signature confirming the authenticity and quality craftsmanship. They are also easy to install. Compatible with all wired doorbells. Mounting hardware included.