This Federal Signal Explosion proof resonating horn is constructed for safe use in hazardous environments. It is enclosed in heavy duty die-cast aluminum housing which is tapped for 3 /4 in conduit. Federal Signal Model 55X is a resonating electric horn which produce sound by means of a diaphragm which resonates a column of air. The Model 55X is available in 120VAC. The 55X is UL Listed for Class I, Division 1, Groups C & D; Class I, Division 2, Groups C & D; Class II, Division 1, Groups E, F & G; and Class III. A five minute duty cycle applies. This resonating Explosion proof horn is designed for locations where the danger of explosion or fire exists, such as refineries, laboratories, mines and grain elevators.