DaveH
Striker
I have found the ultrasonic repellers do a job in my garden, but I only get cats on the veggy patch where cats dig and crap in any lose soil. Once the plants grow there is enough coverage that they don't bother. They need 4xAA batteries, but I buy rechargables so it keeps them cheap to run. The only downside is I can hear the clicking if I'm out there gardening. I tend to just point them to the fence and stick them back in position afterwards. It would not work if they were pointing to my lawn or patio - it would drive me nuts.