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 Easily deal with various places: In villas/apartments/office buildings/hotels/nursing homes and other places 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