wireless doorbell p5726 (without battery)

Way of transferring wireless bells button reach 100 m number of melodies 25 way of pairing automatic pairing - self-learning special function without battery key optical signaling on bell yes optical signaling on button no maximum ring volume of 85 dB option to add another button no number of buttons in the package 1 pc additional (spare) button no waterproof button yes power button without power number of receivers in a package 1 pc volume control yes, 3 levels transmission freq