The Main Console will immediately sound either a beep in the alert mode or a siren in the alarm mode when a sensor is triggered. It is compatible with up to 16 sensors and can be programmed in 4 diff erent zones. The red LED will fl ash and indicate which zone has been triggered. The Main Console comes with a 105dBm Built-in Siren and a Backup Battery feature in case of power outages.The Main Console works as a Indoor Siren for the SkylinkNet Alarm System.