Latest RF Push Rechnology and Battery FreeThis 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 LevelsOur 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 AlarmThis 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 ensures that you never miss a visitor, even if you are a few rooms away or on another floor. Easy Installation Connect Simply plug the mini receiver into a plug and attach the transmitter to a wall with the Our doorbells can be used for home, apartment, school, country houses, office and more. This battery-free wireless doorbell also makes a great Christmas, birthday or anniversary gift for any home or business owner. Transmit Power: Auto -powered Doorbell receiver power supply: AC 110-240V, 50/60Hz Receiver power consumption: 0.25W Ringtones : 38 melodies Volume levels: 4 levels Transmission range: up to 152 m (in open area) Operating frequency: 433 MHz Operating temperature: -4C to 140C