Extremely easy to install....just needed an outlet. There are several volume levels, We needed the loudest volume, which is very loud. We chose a high pitched tune. Exactly what we needed for hard-of-hearing elderly parent. Highly recommended.
The doorbell receivers are smaller than I expected, but as loud as I had hoped they would be. The installation instructions were excellent and worked, easily, the very first time. I do wish the installation instructions were sent in a printed manual that was somewhat larger.