Are you kidding me.  The Nathan AirChime P3 horn is constructed of a Sand Cast Aluminum Manifold and Sand Cast Bells providing a Stunning Mellow Tone that only Sand Cast Horns cam make.  The Genuine locomotive horn features Stainless Steel diaphrams to prevent rust.  These are the only Sand Cast horns we sell and provide an unparralleled railway train horn sound.  Features heavy duty sand cast aluminum construction, exclusive p-series mellow tone locomotive acoustics, large one half inch air inlet for excellent air flow and reversible bells for custom configuration.  SHIPPING IS FAST AND FREE.  Available in aluminum or Black Finish.