Can't remember what brand we bought. (Package with the unused ones are up in the guest room.) Only have one plugged in -- have a problem finding outlets where they fit properly. We've had the one plugged in for a number of years. Totally useless as near as I can figure. No effect on the flying squirrels (which is what I was hoping for). None on insects, either.

On the other hand, the cats are unaffected and so are we. There's a very quiet clicking noise in the guestroom.

Maybe one needs to use all of them?

Oh, it also didn't appear to upset the bats in the ceiling either.

Linn