The wireless doorbell offers a wide selection of 60 melodies and 5 volume levels to meet your needs for different occasions. Flashing lights with audio alert indicators which are easy for people including the hearing impaired to noticeOperating range up to 500ft / 150m in an open area, ensures you hear and answer the doorbell in time. You will never miss a visitor even if you are a few rooms away or on another floor. Easy to install with the double side adhesive tape or the screwsEasy to install. Just plug the receiver into a power socket and attach the transmitter to the door, you don`t even necessarily have to make holes or damage anythingThe button is waterproof, don't worry about extended use Specifications: Model: FA12Music: 60 melodiesVolume: 5 levels (can be adjusted to only flash)Transmitter: No battery required, press to generate electricityReceiver: Lights up only when the bell ringsTransmitter size: 70mm * 46mm * 24mmReceiver voltage: Plug in the power supply for use (AC110V/220V)Receiver size: 70mm * 70mm * 22mmRemote control distance: 150M straight line on the ground (data from the factory laboratory) Package included: 1 x Transmitter 2 x Receivers 1 x English User Manual 1 x Pack of Installation Accessories