Door Bells & Chimes features: Home Wireless Self Powered Doorbell No Battery Required Button Plug Receiver 150M Remote Smart Calling Bell| Doorbells(black) Features and specifications 1.Press the button, super learning code can freely learn to match, can be unlimited matching receiver. 2.Instead of using a battery, the button converts kinetic energy into electrical energy and sends a signal when pressed. 3.The Transmitter can work normally in snow or high temperature environment, waterproof and dustproof. 4.If multiple buttons are paired with one or more receivers in the same system, each button can be set to a different ringtone. 5.Power-off memory function: Turn the power on again after power off, no need to re-adjust and lock the ringtone. 6.The receiver is available in a variety of plugs, suitable for most countries. 7.Eye-catching backlight flashes when someone pushes the doorbell. Particularly suitable for the elderly, deaf, and pregnant women. 8.The receiver voltage is 220v. 9.The receiver is a distance of 150 meters (in an open area), which may be affected by the environment and obstacles. 10.The receiver has 60 ringtones to choose from, and the volume is 0-110db in 5 levels. 11.Just plug the receiver into an electrical outlet,the push button transmitter can be stick it to the door with provided adhesive tapes. 12.Transmitter size:70*46*24mm,Receiver size:92*62*32mm Note: The button cannot be placed on an iron door because it will interfere with the signal. If the receiver does not ring when the button is pressed after receiving the doorbell, please pair the doorbell.