Physen Model CW Waterproof Wireless Doorbell kit with 3 Push Buttons and 2 Plugin Receivers Operating at 1000ft Range,4 Volume Levels and 52 Melodies Chimes,No Batteries Required for Receiver 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 Update:Newest version push button is waterproof/weatherproof,you can install the transmitter outside.CE,FCC,RoHS certified. Wireless Distance: Operating range from 500 to 1000 ft(1000 ft in open area).Remote push button is rated IP33 waterproof and acceptable for outdoor use. Receiver Volume:4 levels of adjustable volume from 25-100 dB [much louder].Offer 52 elegant or custom music,from the traditional"Ding Dong" to various well know chimes [more choices] Easy Installation: just plug receiver into an electrical outlet and put the double-sided adhesive tapes at the back of the button,also you can use screw to fix it.CE,FCC,RoHS certified