Features:No battery required, 150 meters long distance, deep waterproofing, fourth gear volume, 38 chord music.Easy to install, the doorbell is installed on the outdoor wall, the receiver is plugged into an AC100-240V household power socket.penetrate 3-4 walls and has a wireless range of up to 150 meters. It is suitable for large houses in open areas, including villas and apartments. Offices, stores, warehouses, etc.38 chord songs with adjustable fourth gear volume. When sleeping, the doorbell can be muted.Waterproof, don't worry about extended use in heavy rain.Specifications:Item: Wireless DoorbellColor: WhiteMaterial: ABSPower Consumption: 0.25WWireless Frequency: 433MHzWorking Temperature: -10 ~45 Volume: 50dB/1mWireless Distance: 150 metersPackage Size: 9*7.3*7cmPackage Weight: 139gPackage List:2* Doorbell1* Receiver