WHM01 UK Plug Adjustable Volume Door Bell Kit with 1 Transmitter+1 Receiver - White Instead of using a battery,the button transmitter converts kinetic energy into electrical energy and sends a signal when pressed. No need to worry if the battery has power,so you won't miss important visitors It also has 38 kinds of ringtones for you to choose from,you can select the music you want according to your preference Easy to install. Just plug the receiver into a socket,and mount the button transmitter on the wall or anywhere you want Suitable for any home,townhouse,apartment,office,school,hospital,hotel,etc Waterproof design,can withstand adverse weather conditions without losing its functionality It is not only a doorbell,but also a pager. It can be installed beside the bedside of the elderly/babies/pregnant women. If necessary,just press the button to notify people Specification: Working voltage: AC 100V-230V 50/60Hz Working frequency: 433.92MHz Modulation method: 00K Standby power consumption: 0uA Standby power consumption: 0.25W Music: 38 ringtones Controllable volume: ≥50dB/1m Receiving distance: ≥150 meters (open space) Receiver operating temperature: -10℃ ~ 45℃ Transmitter operating temperature: -20℃ ~ 60℃ Receiver size: 66*50*55mm Transmitter size: 70*46*23mm Package included: 1 x Receiver (UK Plug) 1 x Transmitter 1 x English User Manual Other things not included