ADVANCED TRANSCEIVER TECHNOLOGYThis doorbell uses microchip with advanced wireless transceiver technology for stable and reliable. When pressing the button, the doorbell will immediately receive the signal and make a sweet melody. 32 RINGTONES, 4 VOLUMESThe receiver has 4 adjustable volume and 32 melodies for different needs. LED flashes when someone presses the doorbell, convenient for the deaf, pregnant women and the elderly. HIGH PERFORMANCEMade of superior plastic which can withstand high temperatures and interference. Its waterproof and dustproof feature make it suitable for indoor and outdoor use. The battery-operated doorbell button also has an extremely low power consumption, ensures an unparalleled long lifespan. EASY TO USE Simply plug the receiver into the socket and insert the supplied battery into the bell button then fix on the wall or door frame with the supplied adhesive tape. It will not interfere other devices. WIDELY APPLICATIONUp to 200m long range, great for large houses including villas, apartments, offices, shops, warehouses, etc. (Note: the receiver can learn up to 30 transmitters (433MHz) but the doorbell button only works with the receiver.) Style 1: doorbell button + doorbell main unit Style 2: doorbell button + doorbell mainframe + doorbell mainframe