Self-generating transmitter: No battery is needed, A finger press can trigger the generator to convert into electrical energyLong-distance transmission has strong penetration: Strong signal penetration can be used in offices, offices, homes, shops, factories, and other occasions5 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 neighborsThe receiver can distinguish signals from different transmitters: Through different transmitter signals, let the receiver emit different bells to easily distinguish which door has visitors Specifications: Model: FA28Music: 60 music tracksVolume: 5 levels of volume (adjustable to flashing light only)Transmitter: Press to generate power, no batteries requiredReceiver: light only when the bell ringsTransmitter size: 74 x 40 x 20.3mmReceiver voltage: plug-in power use (110-220V)Receiver size: 90 x 56 x 20mmRemote control distance:150m in a straight line on open ground Package included: 2 x Receiver 1 x Transmitter 1 x English Instruction Manual 1 x Installation Kit Other items not included