SELF-GENERATED ELECTRICITY - This is a wireless doorbell, but no more battery or battery drain! By pressing the push button, it converts kinetic energy into an electrical signal to ring your wireless doorbells. So no more worrying about your push button running out of batteries and no more hassling with buying weird batteries to power your push button. You will always hear your doorbells! IP64 WATERPROOF & LED TIME DISPLAY SCREEN - IP64 waterproof rating makes the transmitter resistant to rain and harsh weather, made of ABS+PC plastic, durable to use, works under temperatures between -20°C to +65°C. LED time display screen, time will appear when the receiver is not ringing, can be used as a clock 38 MELODIES & 4 VOLUME LEVELS - Select your favorite sound from 38 different chimes and the volume you like from four levels (0-110dB). And the memory function of our wireless doorbell outdoor can memorize the last melody and volume level and time after a power outage 150 METERS WIRELESS