Very disgusted that this unit won’t ring the existing door chime!!! Purchased at Lowes, looked over and over the display info, the packages, and talked to clerk. Concluded that the ONLY difference between this and the more costly unit was that the more costly unit COULD be battery powered. NO INFO AT ALL that the “wired” model could not operate my existing chime. So… after full installation, now it will be returned and I’ll burn a more hours getting the right unit just because you couldn’t say as much on the package. What incompetence in packaging!!