This is a product that works fine for its purpose and then also works when it wants to on its own.  When I read on other reviews that the chime started to ring on its own, I assumed that they simply didn't replace the batteries on a timely basis.  However, my new chime started spontaneously and magically ringing on its own during the first week I had it in place by the door.  I put it on my dresser, and now every once in a while for no apparent reason it chimes.  I plan to return it.  Who wants a doorbell in the house that rings when the dog isn't anywhere near the door?