Characteristic: ◎ The wireless digital doorbell sound is melodious and tuneful , there are three kinds of sounds, many kinds of bel canto are suitable for all kinds of personages' choosing even more. ◎ The appearance is compact and uniquly . ◎ The remote control range is 100 meters . ◎ By installing it is simple and easy, you can lay it anywhere . Its built-in button battery can be used for one year .It's built-in button battery can spend one year ( 20 Times /1 day), because the product is wireless, so does not influence the environment . ◎ The all-weather anti-interference system is designed, 1/100000 of the numbers encrypt the code , remove the neighbour and external world from interfering completely, there is no vexation sounded definitely. ◎ We design it at Saving electricity module . Dimensions: Receiver: 10.3 ?10 ?3.2 cm Transmitter: 8.7 ?8.6 ?3.4 cm Outer packing: 48 pcs/ctn Carton dimensions: 57.5 ?53 ?28.5 cm N.W.: 12 kg G.W. 13 kg