Cordless Wireless Remote Control Chime Door Bell, White, V001A Wireless system,Super long receiving distance DIY design make you not need to seek the help from professionals,and you don't need to set the line or to excavate a hole It is easy for installation.You can install it everywhere you like according to your apartment Unique product design idea is continually melted in by the modem element,which makes the product more Energetic 40m 4D remote control distance is easy for your installation and you can enjoy the music in your space and share the happiness of knowing the arrival of your friends There is a function to control volume, you can easily set it up by switching the external switch.