Elecforu Model FXA Wireless Mains Plug-in Doorbell Door Chime Operating At 500-feet Range with Over 50 Chimes, No Batteries Required for Receiver, (White) Supports wireless range up to 300 meters in open area. Over 50 ring tones for your choice.Four levels of adjustable volume from 65db to 110db. Suitable for home life, office building, hotel service and etc. Humanized design; Easy installation,plug and play. CE,FCC,ROHS certified; safety and enviromentally friendly.