Vibratone Electronic Horn - Fire Regulated 16-33VDC, General Purpose Signal 12-24VDC. Coded or sustained tones. No duty cycle or interval limitations. 99 dBa at 10 feet on axis (109 dBa at 1 meter on axis). Four wire terminal block and supervisory diode. Type 4X when installed with Panel Mount Gasket (included) or optional Non-metallic Weatherproof Backbox (Model WB-NM). Marine Rated. CSFM Approved. UL and cUL Listed. UL Fire Listed and ULC Canadian Fire Listed.