Differentially set ringtones: Different buttons set different ringtones, easily distinguish between front and rear doors. Built-in 38 welcome music/3-level volume adjustable. This doorbell does not need wiring, plug and play, convenient and practical, easy to install The receiver is suitable for direct plug-in, the applicable voltage range is 100-240V 50/60Hz. Applicable scenarios: residential, hotel, villa, hospital. Function: Learning Code Remote control distance: Indoor distance is about 50 meters (without partition),Outdoor open space is about 100-300 meters. (This data is the experimental test distance. The actual distance is affected by the applicable environment and obstacles. The more obstacles, the shorter the distance. The actual distance is subject to the experimental environment distance) How to use: Packaged products are paired before they leave the factory, and no need to pair again. Pairing method: The receiver socket is plugged into a regular household socket. When the