I'd like to come back to my first observation, which obviously wasn't accurate. The device works and is efficient. The noises vary and are therefore sometimes perfectible and other times not. As far as battery consumption is concerned, I haven't touched anything in two months. I haven't had any weasel damage since using it. I therefore recommend this product...
Too expensive! I ordered and received the same product in Munich, including batteries and marten spray, for considerably less than the Migros price.