Works, but not at the specified size

The Mole-defense comes in a small cardboard box and includes besides the actual defense, only the manual. This in several languages, including German. The manual is clear and explains all the relevant facts simple and understandable.
For commissioning three batteries are needed in the size D, which are not included. It has to be unscrewed only the upper screw cap and the batteries are inserted, already sounds a clear sound, which not only moles scared. The sound can be heard for two seconds before he silenced forty seconds. In the bottom of the sound still can be heard, you get used to it so that you can not hear him over time.
The effect of the mole and vole defense is entirely given, though not nearly as much as the manufacturer would like it and indicates. Whether the frequency actually change, I can not say. In any case, it disturbs our animal kingdom and the molehills, and the holes in the garden actually take off.
For full effect it should be noted that the mole-defense is to be set repeatedly or how I did it simply buy more of these protective measures designed to ensure this great price, the easiest method.
Conclusion: getting used to defense, which at the end of work, however, not quite as extensive as specified by the manufacturer.