"Years ago, while finishing my basement, I didn't think to put a three-way switch in the stairway. I decided to just live with it since I didn't feel like cutting holes in the walls and ceiling to run the wiring...it wasn't worth the hassle to me. Then I discovered this product, and it seemed too good to be true. Yes, it's expensive, but it works beautifully, and I was able to install the switches in existing switch boxes. I had no problems with the install and everything works like magic. A great product!"