Rodent deterrent?

[ChocFudgeCake]

I saw in the Argos catalogue a little device that emits a sound (audible just for mice)that makes them go away. So the garden door can be kept open and they won't dare come in. Anyone heard about this or used it?
Thanks.

It's not all that effective tbh, a noisy toddler works much better. We had a mouse invasion and they didn't seem to be at all bothered by the noise thing, although that could be because dh kept putting things in front of it which probably blocked the sound quite a bit.

it can work but apparently if you already have mice they will get used to it

We tried one of these and it did nothing - total waste of a tenner, so I wouldn't bother if I were you. Only thing that worked was copious amounts of poison (hidden behind kickboards of kitchen units so dcs safe - that is also where the mice tend to run). Also, since a very friendly cat moved in a few doors down and started visiting regularly, wiping his scent everywhere, the rodents (touch wood!!) appear to be giving our house a wide berth.