Ding dong! Forget the scratching, barking, and whining! Easily teach your dog to ring the mighty paw smart bell to communicate potty time. It's the premier solution to all of your dog potty training problems. As a bonus all of your friends and family will be amazed at your dog! Can choose from one (1) transmitters or two (2). No battery charging and/or battery replacement not required. Wireless transmitter does not require power/electricity to operate. Receiver plugs into standard 110v outlet. Water-resistant no wires or plugs makes the transmitter great for indoor or outdoor use. Features 3m adhesive for wall/door mounting no screws or tools necessary. Four (4) different volumes to choose from. Can select from 38 different ringtones. Transmitters and receiver communicate as far as 1000 feet from each other when indoors. Easy to use for pets of any size requires just .75 lbs of pressure with nose or paw to ring the bell. Training guide included.