Generally not bad

As this is not my first 'mole fright' is I have good, many comparisons.
Basically: not every device works the same everywhere (for whatever reason).
I've thereof ordered these four units, one of which did not work at the very beginning two.
These two were replaced promptly and courteously, 4 stars for the service (at a final inspection, however, this would not even happen ;-) !!)
Since all devices have a different frequency sound, I already know that at least. 1-2 will have no effect. The two already put a week at the bottom have the mole scared only a few feet - they are much too quiet !!! Means I would have to buy more - but I had until recently, for two years, a battery-powered device in the floor (for 26.00) that was much louder and has all 30sec. vibrates and the à with only 3 battery sets 3pcs. in two years, the two devices before (solar equipment) about one and a half years have held, were loud, but also more expensive. I had a total of 7 years 6 Different devices and unfortunately these are the 'worst' - only times the two most recently delivered today I used early, wait and see what happens, they are so quiet, like the other two - of 4 would I expected more than just a 'scare' to a few meters, the meadow is approximately 340qm great, next time I will again invest some extra money!