Has one tried those little boxes that you point at a dog and it supposedly makes them stop barking?

It’s supposed to use super sonic sound waves or something. On one of our local news channels they have this show once a week called, “Does it work?” They try out all the stuff that’s advertised in infomercials. My husband said that they said it does work.

Assuming it does work, my next concern would be, does it hurt the dog’s ears? And also, how in the world would it prompt them to stop barking?