The Shocker horns are the loudest, most reliable train horns in their class! These horns are crafted from fiberglass reinforced ABS plastic with stainless steel diaphragms that will not rust. They not only have a genuine train horn sound, but sound at 148db at just 100 PSI. The lack of a shared manifold makes these horns capable of being installed separately, so installation is a breeze on any size vehicle. This product includes the four Shocker horns, an electric air valve, airline, brass fittings and mounting hardware.