We love it as it finally solves our needs instead of giving up our 2 sets of the alertmaster system due to 3-time worn out doorbell. It works well with our current system. The door knock device now is outside as a doorbell instead of putting on the door inside. It replies well when someone pushes it.

Love this product!~ Much better than the doorbell which is harder to hang and in my experience falls off. I can put this on the inside of the door and not worry about it being exposed to bad weather. The holder could be much better designed, though.