Insert the plug of the iSmartAlarm AS3G into the wall socket and place the extra siren at any desired location in the house. The siren is suitable for iSmartAlarm alarm systems. With a detection, a sound signal of 110 dB sounds. Do you want the siren in a place where there is no power point? Then it also functions on 3 AAA batteries. Of course, these also serve in the event of a power failure.