Recently the number of local moggies has risen - and at least two have
become regular habitués of our garden. And most especially, our borders
when they have a need for a toilet.

Searching around for an answer, a relative recommended one of the Cat
Guard devices. (They suggested a specific one that we have been unable
to find.)

I found several ultrasonic devices he

http://www.primrose-london.co.uk/cat-deterrents-c-102.html

Any opinions on effectiveness?

The area we need to control is fairly small. Any reason not to go for
the cheapest?

In general they seem to be incredibly expensive for a fairly simple set
up. (Not just the devices but the mains power supplies.) And I am deeply
sceptical as so many devices like this (e.g. against mosquitoes) have
been flogged without any proof that they work. And if the noise they
make is audible (as some people report), maybe it would annoy us and/or
neighbours?

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org