The Signolux Visual Alert system is portable for use throughout the home or can be wall mounted. The wireless alerting unit operates up to 200 metres away from the Bell Push on the 868Mhz frequency. The receiver has 8 different indicators meaning that you can be alerted to different events within the home by adding different transmitters to the system. The receiver will alert you using very loud selectable chimes (>90dB), a bright flashing light and also visual indication symbols. This system comes with a Doorbell Push & a telephone transmitter, this telephone transmitter can be plugged into any telephone socket in your house and when the phone rings it will send a wireless signal to the Signolux Visual Alert Receiver which will then indicate the telephone symbol, will ring like a very loud telephone and also flash. What's in the box? Door Bellpush.Flashing and sounding receiver.Telephone direct transmitter.All Batteries.