【Latest RF Push Rechnology and Battery Free】This wireless door chime is self-powered, requires no cables or batteries, protects the environment and saves you money. When the transmitter is pressed, it generates electric current itself and sends a stable signal to the receiver. Never worry about damaging the wall or doorbell again when changing batteries! 【38 Ringtones & 4 Volume Levels】Our wireless stereo doorbell speaker delivers rich, clear sound. It offers a wide range of 38 ringtones and 4 volume levels (including mute) to suit your personal taste. Press and hold the volume button to return to the first ringtone (Dingdong). With memory function, the wireless bell remembers your last settings after power failure. 【No Crossalk and False Alarm】This small wireless doorbell has strong penetrating force and anti-interference. The range for multiple obstacles is up to 152m (500ft) and in open areas up to 305m (1000ft). It does not affect other devices in your house or neighbors and