The Federal Signal Model 56 electric horn produces sound by means of a diaphragm which resonates a column of air. Because the output is greater than that of a vibrating horn resonating horns can be used wherever a louder more powerful signal is required. Model 56 features a corrosion-resistant cast aluminum housing with a brass projector. These projectors are designed to match the frequency of the vibrating diaphragm to produce a smooth musical tone. The housings are tapped for 1/2" conduit. Model 56 is ideal for both indoor and outdoor use and has a duty cycle of five minutes on five minutes off.