The Doorbell Wireless Home Receiver Does Not Require Batteries Features and specifications: 1.The button supports up to 2PCS, and the receiver supports up to 100pcs. 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 the power on again after power off, no need to re-adjust and lock the ringtone. 4.The transmitter has no screw chuck design, and it can be waterproof and dustproof without rubber ring. 5.The transmitter USE a 23A12V alkaline battery (not included battery). 6.Receiver voltage: 110-220V. 7.The receiver is available in a variety of plugs, US/EU/UK Plug and AU adapters, suitable for most countries. 8.Receiving distance:300 meters in open area. 9.The wireless signal will be affected by obstacles. The more obstacles, the more serious the signal loss. 10.Receiver has 4 levels 20-80db,36 music to choose from. 11.Size:Transmitter 77x46x20mm,Receiver 90x56x20mm. NOTE:The button cannot be placed on an iron door because it will interfere with the signal. Only sell the doorbell in the picture, the rest of the goods are for reference only and not for sale