[Self-Powered Push Button Battery Free ] No battery required wireless doorbell. The push button generates electricity by itself. No more worrying about battery replacement [ Easy to Install ] Just plug the receiver into the socket and use them easily [ 38 Ringtones Available& 4 Volume Mode & Amazing LED ] Find your favorite Ringtones among 38 Chimes. 4 levels of volume for your space. Flashing LED-Light makes it easier for you to notice the coming visitors [ Suitable for Variable Environment ] The working temperature is from -20° to 60° （-4°F to 140°F）. Multiple Ringtones and LED light make it sutable for home office store school hospital and other spaces [ Long Operating Range ] Un1que self powered calling bell operating range is 300m / 1000ft in open areas. You can install it in any corner in your space [ 1 Year Warranty ] Enjoy peace of mind with a 1 year warranty