CACAZI FA28 Smart Wireless AC Doorbell,2 Transmitter + Receiver Self-Generating Doorbell - White/EU Plug ?Self-generating transmitter: No battery is needed,A finger press can trigger the generator to convert into electrical energy ?Long-distance transmission has strong penetration: Strong signal penetration can be used in offices,offices,homes,shops,factories,and other occasions ?5 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 ?The 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: FA28 ?Music: 60 music tracks ?Volume: 5 levels of volume (adjustable to flashing light only) ?Transmitter: Press to generate power,no batteries required ?Receiver: light only when the bell rings ?Transmitter size: 74 x 40 x 20.3mm ?Receiver voltage: plug-in power use (110-220V) ?Receiver size: 90 x 56 x 20mm ?Remote 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