Zero stars would be appropriate.

Expensive, bad and not working. Otherwise, we can not describe it, unfortunately. Our marten disturbs the extremely loud, like interval Piepesen not. For the neighbors and especially the device in children, babies and dogs seem to trigger (strong) ear pain. We would not be surprised if the device is not "marketable as hazardous to health".
Our neighbor has four beeps (two times the X4-Life MMV1014 Mobile marten distributor, one of the front tires and the rear tires) and just like us, regular visits Marder

For being with us absolutely shows no success, except stress with the neighbors and pet owners, every euro is too expensive for the Marder Schreck.