Quick and easy to install and use. Works within a range up to 100 meters in open space. No cumbersome wiring needed to be installed. With 32 melody music. Comes with a double-sided adhesive tape for your convenience. Remote button battery: 1x 12V 23A battery (included). Doorbell size: 105mm x 75mm. Remote button size: 75mm x 43mm. Build in double speakers, make sound clear, especially suitable for homes, offices, factories, hotels, etc.