Veio sem custo, opera, porém, é necessário estar perto, a menos de 5 metros.

Unfortunately, the ultrasonic waves aren't strong enough and have no effect on the neighbor's dog, which barks at everything that moves!

This product is likely intended for dog owners to control or train their own dogs. However, I purchased it to stop my neighbor's dog (and others nearby) from barking. Here's what I've experienced... When used from a distance greater than 10 meters, it doesn't seem to work at all, even after trying both modes repeatedly. When I get closer than 10 meters, some dogs stop barking and leave, but my primary concern, my neighbor's three small poodles (aged about 1 and 2 years old),show no reaction whatsoever! Initially, they might have been slightly surprised, but now they bark even more after repeated use. Additionally, my two cats, who are the main target of the poodles' barking, are more sensitive to the device, and it scares them even from a distance. This confirms the device might repel cats. Ultimately, I conclude that, in my specific situation, this device is essentially a very good, but quite expensive, flashlight.

This product is excellent; I tried it out from a distance of 10 meters, and it functions correctly.