Features: * Easy to use, just plug the mini receiver into a socket and fix the transmitter on a wall with the double-sided sticker. * 150 M/ 500 FT ultra long wireless range, enables you not to miss a visitor even if you are in your neighbors\' house. * 3 Adjustable volume levels with a setting of 50dB per meter, meeting your different needs for ringtone volume. * 38 Music melodies are included, you can press the music selection button to easily choose the music you want. * Dustproof and waterproof , its working temperature is between -20 C to 40 C, which withstands various harsh weather conditions.