Expel any voles

This Wühlmausschreck works perfectly, even with less light in autumn or winter, the battery loads still on and the thing beeps his rounds. However, the vole does not really matter, the mockery was a new hole for the construction of about 15 cm from the Wühlmausschreck. Perhaps there are voles do not like the sound, my seem to love Him. Too bad!