Wolo (853) Philly Express Truck Train Horn Will give any vehicle the powerful sound of a train air horn The four trumpets and mounting base are metal triple chrome plated and designed smaller to fit into engine compartments that are unable to accommodate a full size train horn Built into the horns base is a heavy-duty, chrome plated 12/24-volt electric solenoid valve Horn comes with mounting hardware and instructions in English / Spanish Requires an on-board air system, (recommended Wolo on-board air system Model 800)