It makes a lot of noise but I didn't see any results on the birds. The battery operation is not reliable at all, it only works continuously with electricity.

I tried it in my yard to deter stray dogs that come daily, unfortunately I didn't see any improvement. I continued to find dog waste in the yard every day, which indicates that they are not bothered at all by the device's function. The device was set to the highest level for dog operation.

Ultrasounds do nothing to cats, the regular sound scares them but it's not what I wanted because it bothers the neighborhood.

I am satisfied.
I only operate it with the motion sensor and permanently connected to power, although it also works with batteries if you prefer.
The only downside for me is that even at the lowest volume, the sound it produces still slightly bothers me.
In other words, the sub-sound is somewhat noticeable to my ear

The ultrasound seems to work properly with cats and dogs. To test it, I activated the photocell manually several times and indeed, after a few seconds, the animal moves away from the garden. It takes a little searching to find the right position for the frequency dial (in my case, it didn't work as well in the position recommended by the instructions, but it worked in the middle of the relevant range for cats and dogs). Currently, I have it plugged in (very practical), but therefore in a position where the photocell cannot work. In the next few days, I will put it outside with batteries and see how well the photocell works and its resistance to the sun. I will update the review accordingly.