•Operating range up to 150m in an open area when there are no obstructions •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 •The receiver has 5 levels adjustable volume, which can be adjusted to flash only •It also has 60 ringtones for you to choose from, you can select the music you want according to your preference •The bright light indicator of the transmitter offers additional assistance for the hearing impaired •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 Specification: •Music: 60 chimes •Volume: 5 levels •Transmitter: no battery required, press to generate electricity •Receiver: plug into the power socket (AC 110V-220V) •Transmitter size: 86*86*22mm •Receiver size: 92*62*32mm •Remote distance: 150m (straight line distance on open area) Package included: •1 x Receiver •2 x Transmitters •1 x English User Manual •1 x Installation Tool Kit •Other things not included