Connected doorbell and video door phone - Universal - Three automatic doorbells without battery.(The black) Highlights Universal Three automatic doorbells without battery.(The black) One for three without battery self-powered doorbell Features and specifications: 1.The button takes supports up to 20 pcs and the receiver supports up to 100 pcs. 2.If multiple buttons are paired with one or more receivers in the same system, each button can be set to a different ringtone. 3. Power off memory function: turn it on again after power off, no need to reassign and lock ringer. 4. The transmitter has no screw chuck design, and it can be waterproof and dustproof without rubber ring. 5.The transmitter Use 23A12V alkaline battery (battery not included). 6. Receiver voltage: 110-220-240V. 7.The receiver comes in a variety of plugs, US/EU/UR/AU adapters, suitable for most countries. 8. Shorten the distance: 300 meters in the open area. 9.The wireless signal will be affected by obstacles. The greater the obstacles, the more severe the signal loss. 10.Receur has 5 levels (can be mute) 0-110DB, 60 music to choose. 11.Size: 75x51x20mm transmitter, 95x65x24mm receiver. Note: The button cannot be placed on an iron door as it will interfere with the signal. Only sell the doorbell in the picture, the rest of the goods are only for sale, not for sale