In reply to C£ Chullain
I put one in garden two days before Easter weekend last year. On returning from long weekend, garden was free from sh*t and haven't seen a cat there since. Also stopped the local fox population (whose sh*t smells even worse). Ran out of battery 6 months later but haven't replaced and cats haven't returned.
Disadvantage, my partner could "feel" the sound it emits and it made him want to run away too!
You can alter the pitch the noise is emitted at and I have to admit when it's lower range it is pretty offensive. Just turn it up higher til you can't hear and should be fine.
Post edited at 10:25