Self-generating transmitter: No battery is needed. A finger press can trigger the generator to convert into electrical energyNot just a doorbell but also a pager: The elderly, children, and pregnant women have needs, just click to know, sleep at night with peace of mind Easily deal with various places: In villas/apartments/office buildings/hotels/nursing homes and other places5 levels of adjustable volume whatever you want: The doorbell has five levels of volume, which can be adjusted freely. (Volume can be adjusted, light reminder)Anti-interference, no crosstalk: Digital circuit design, multiple sets of use will not cause cross talk, effectively avoiding the troubles caused by mutual interference between neighbors Specifications: Model: FA78Music: 60 music tracksVolume: 5 levels of volume (adjustable to flashing light only)Transmitter: No batteries required, press to generate powerReceiver: Light only when the bell ringsTransmitter size: 74 x 40 x 20.3mmReceiver voltage: plug-in power use (AC110V/220V)Receiver size: 84 x 52 x 29mmRemote control distance: 150M in a straight line on open ground Package included: 1 x Receiver 2 x Transmitter 1 x English Instruction Manual 1 x Installation Kit Other items not included