Edwards Signaling DUPLO series is a motor driven weatherproof siren. This siren’s unique output signal may be pulsed on and off to achieve a wailing tone. The siren's sound is produced by a multi-bladed, nylon impeller which pulls air through openings located on the front of the unit and pushes the air out through radially positioned vents. The DUPLO is designed for bracket mounting using the housing bracket. The signal is supplied with wire leads for connection in an appropriate electrical box. Designed for outdoor use. Applications include local weather and emergency warning, area evacuation, security alert, process control, and equipment shutdown notification.