This product contains one front door push button and two receivers. That means you can have 1 receiver unit plugged in downstairs and 1 unit plugged in upstairs and when the front door unit is pressed both units ding dong. With a choice of 32 different ring tones and the ability to adjust the volume these door bells are perfect for all installations. Very simple to install, just use the double sided tape and stick the front door unit onto the best position, and plug each receiver into a power point and you are done. Comes with a 12 month warranty.