1Made of good quality plastic with waterproof processing, very durable, suitable for outdoor use 2Built-in 51 melodies, you can choose the one you like. 3The transmitter needs no battery, it can turn the force of pressing the doorbell into electricity. The receiver supports wide voltage of AC 100-260V 4With 4 levels of volume, the max. decibel is up to 95dB, the older people can use it without trouble 5Stable and fast frequency, 120-150m transmission distance without latency or lag
