Wolo (810 Challenger EV Roof Mount Air Horn - Electric Solenoid Valve Operated High pressure roof mount air horn powered by an on-board air system Produces an ultra-powerful, big rig alerting sound, controlled by a 12-volt heavy-duty electric solenoid valve The horns base is painted black enamel and both trumpets have a bright chrome finish, which will dress up any vehicle big or small Installation is made easy with Wolos new flexible inlet hose, with brass fittings, that is hidden from view Included is a two piece on-board high pressure air system consisting of a 2-1/2 liter steel air storage tank, with a built-in pressure switch and a heavy-duty high-pressure compressor