【Latest RF Push Technology & Battery Free】This wireless doorbell is self-powered, no cables or batteries required, environmental protection and money saving. When the transmitter is pressed, it will generate electric current by itself and send a stable signal to the receiver. No more worrying about damaging the wall or doorbell when changing batteries! 【36 Ringtones & 4 Volume Levels】Our wireless stereo doorbell speaker delivers rich and clear sound. It offers a wide range of 36 ringtones and 4 volume levels (including mute) to suit your needs. your personal taste. Press and hold the volume button to return to the first ringtone (Dingdong). With memory function, the wireless doorbell remembers your last settings after a power outage. 【No Crosstalk & 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 home or