Elecforu Model Fxb Wireless Doorbell Waterproof Cordless Chime Operating At 500-feet Range with Over 50 Chimes, No Batteries Required for Receiver, (White) Receiver:easily plug into an electrical outlet (Please DO NOT plug receiver into UPS units); Transmitter:Powered by 12V A23 Alkaline battery(Battery Included) Over 50 ring tones for your choice.Four levels of adjustable volume from 65db to 110db. This is not only a simple doorbell, but also can be used as professional pager to look after your family;Suitable for home life, office building, hotel service and etc. Unique LED indicator flashes blue light,romantic and elegant,from which you know somebody is outside your door even under low volume Adopt learning mode under which you can pair push button with door chime freely according to you needs