Instead of using a battery, the button converts kinetic energy into electrical energy and sends a signal when pressed; don't worry if the battery has no power, so don't miss important visitors The transmitter is installed outside the door, the receiver is installed on the power socket, press the transmitter and ring the bell, and the receiver immediately rings and flashes to remind Long distance barrier-free 150m strong singal penetration The doorbell sound is not just a simple "ding dong" sound, it can also realize the free switching of 60 chord music, the sound quality is mellow, and it is pleasant to hear, press the doorbell, and the receiver rings and fashes The doorbell has five levels of volume, which can be adjusted freely Digital circuit design, multiple sets of use will not cause cross-talk, effectively avoiding the troubles caused by mutual interference between neighbors Through different transmitter signals, let the receiver emit different bells to easily distinguish which door has visitors Specifications: Product Brand: CACAZI Music: 60 music options Product name: Self-powered Wireless Doorbell Model: FA96 Volume: 5 levels (You can adjust it to flash only) Transmitter: no battery needed, press to generate electricity Receiver: Light comes on when the bell rings Receiver: plug in the power supply (AC110V/220V) Transmitter size: 74*40*20.3mm, Receiver size: 90*56*20mm Remote control distance: 150M straight line distance on the barrier-free ground (data source factory experiment)