I had a rodent problem in the apt below my storefront and I in desperation got some of these (different brand) and it was a miracle … who knows if they actually went away cuz of this but I am a believer and I want them even though I don’t have any wee critters
I’d bet that the other ones plugged into the wall, and actually were ultrasonically very loud. These, running on a 9V, might be able to be as load and annoying as a mosquito for a few days before the battery goes flat, but the rat would have to be standing on the unit to hear it. If the battery lasts longer than that, you can safely bet that the only thing it’s actually powering is the LEDs.