SIRRA is a universal external siren radio design very appealing. E 'powered by a 230Vac transformer network (included) and a 12V rechargeable battery in buffer. The siren can be used with any alarm center through an external transmitter TSR (included) which, when connected to the central Sirri to send the following commands: PLANT PLACED (indicated by a blinking) PLANT OFF (indicated by 3 flashes) START ALARM (active high-power sound) STOP ALARM (mute sound at high power) Equipped with a radio transmitter on board, the siren is equipped with tamper protection antiapertura / anti-metal and internal security antitrapano.