This set comes with one sending unit and two receivers, which can be placed in two different parts of your home. The advantages are the price and that there are two receivers. The disadvantages are that the receivers are not backlit, so they are not helpful in the dark, and that the clocks on each must be set individually. The units run on standard batteries, and they last long enough to never be a problem. Even with the imperfections, I'd buy them again.