Package contents: 1 transmitter, 1 receiver Latest technology and battery-free: This wireless doorbell is self-sufficient, requires no cables and batteries, protects the environment and saves you money. When the transmitter is pushed in, it itself generates electricity and sends a stable signal to the receiver. Never worry about damaging the wall or doorbell when changing the battery again! 38 ringtones and 4 volume levels: Our wireless stereo doorbell speaker delivers rich and clear sound. It offers a wide range of 38 ringtones and 4 volume levels [including silent) for your personal taste. Press and hold the volume button to return to the first ringtone [dingdong). With a memory function, the radio clock will remember your last settings after a power .NO crosstalk and false alarm: This wireless doorbell has strong penetrating power and anti-interference. Range over multiple obstacles is up to 152 m [500 ft) and in open areas up to 305 m [1000 ft). It won't interfere with other devices in your home or your neighbors, ensuring you'll never miss a visitor even if you're a few rooms away or on another floor. Easy installation: Just plug the mini receiver into a power outlet and mount the transmitter on a wall with the included hardware, including 2 screws and a piece of adhesive tape.< p>Our door ring is suitable for home, apartment, school, villas, office and more. This battery-free cordless doorbell makes a great Christmas, birthday or anniversary gift for any home or business owner.