No Plug-in Battery Wireless Doorbell Features and specifications 1.The button supports up to 8 PCS, and the receiver supports up to 100pcs. 2.The transmitter has no screw chuck design, and it can be waterproof and dustproof without rubber ring. 3.If multiple buttons are paired with one or more receivers in the same system, each button can be set to a different ringtone. 4. Power-off memory function: Turn the power on again after power off, no need to re-adjust and lock the ringtone. 5.Eye-catching backlight flashes when someone pushes the doorbell. Particularly suitable for the elderly, deaf, and pregnant women. 6.Uses machine-learning to prevent interference from other wireless transmitters. 7.The transmitter USE a 23A12V alkaline battery (not include battery). 8.The receiver is available in a variety of plugs, US/EU/UK Plug and AU adapters, suitable for most countries. 9.Receiving distance:300 meters in open area 10.The wireless signal will be affected by obstacles. The more obstacles, the more serious the signal loss. 11.Receiver has 4 levels(can be mute) 0-80db,38 music to choose from. 12.Size:Transmitter:77x46x20mm,Receiver:90x56x20mm Only sell the doorbell in the picture, the rest of the goods are for reference only and not for sale