Perhaps effective in large numbers and long term.

I bought this for a second home where I had already tried successively poison and other camera ultra sounds less powerful but failed to completely eradicate mice. After 4 days of use repeller WK0300 mode 'strong' (very unpleasant for human ears) I found the appearance of new mouse droppings and I was forced to resort to fags that were much more radical (2 mice captured per night). I left my house leaving 5 devices connected to ultra sounds and hoping (without much hope) that the mice soon abandon the scene. Following later.

Back in my home a few months later I happily noticed the disappearance of rodent and was able to stop the ultra sound equipment. At last the mice did not return. So I change my review, these devices may be effective, but be patient. Rodents remained about 2 months after I installed the first devices. So it is difficult to argue that it is these devices that have cast them from home.