PHYSEN Model CW Wireless Doorbell kit with 3 Push Buttons and 1 Plug-in Receiver Operating Range up to 1000ft,4 Volume Levels and 52 Melodies Doorbell Chimes,No Batteries Required for Receiver 3 remote push buttons and 1 plugin receiver for you to DIY your house and you can program each push button to a different tone so you can know which door is someone at. Operating range of over 500 feet (1000 feet in open area).for a big house,office, hotel service and other areas that is suitable for short-distance wireless environments A perfect use case scenario for this product would be if you have a front door , a back door and a side door, you can program each transmitter to a different tone so you can know which door someone is at Receiver:easily plug into an electrical outlet (no batteries required for main receiver); Transmitter:Powered by 12V Alkaline battery(Battery is Included) Update:Newest version push button is waterproof/weatherproof,you can install the transmitter outside.CE,FCC,RoHS certified.Here at physen,we encourage you to make use of our Worry-Free One Year Warranty Guarantee. A happy purchasing experience is the utmost importance to us and we will happily send a product replacement if any issues arise.