Differentiate the front door from the back door - you can program each button to a different tone so you know where your guests are. For multiple doorway entrances, this is a very handy feature. Further Range - Up to 1000 feet (300m) in open air from the transmitter (150m if there are walls). Whether you're in the bedroom or in the kitchen, our wireless doorbell kit can alert you to someone calling from outside. Never worry about missing a visitor. 45 Melodies and 4 Volume Levels - The wireless doorbell offers 45 melodies to choose from. 4-level volume Use silent mode when you don't want to be disturbed. EASY TO INSTALL - Simply plug the main doorbell into the wall outlet, use the double-sided tape provided or screw in the button. If you have any questions about our products, please feel free to contact us, we will try our best to find a satisfactory solution for you within 24 hours