A disadvantage of the device is that you get it very difficult in the earth. In the picture the thing looks so pretty small, but it's a murder part. One should it dig deep about 40 cm. Who has time dug holes for foundations, know how hard the soil at this depth already.
It would be better in my opinion, an aluminum top was that like a screw drilled into the earth.
The partly bad reviews (not working) may be attributed to a non-optimal positioning of the mole fright. It probably does not help to put the thing somewhere in the middle of the garden. This drives the mole while away, but just once across country. The shock should be best positioned so that the mole tunnels between the device and the point at which the mole to be driven forth, are located. I also put the unit during the brief phase therefore multiply.
As a vole drives her Unwesesen elsewhere, I have now ordered a second device.