After my garden was infested with voles, I was looking for ways to get rid of these. First I tried this solar Pieper. I immediately bought 2 pieces. One of them was after 3 days already on the mind. The second works reliably for 4 weeks, but seems the voles to impress in any way. I have reconnected the device several times, each time new Erdaufwürfe were in close proximity to recognize. In my view, therefore, no real help!