This collar was, on the one hand, reliably effective. When I put it on, my dog would stop barking and go back to his kennel looking upset. It seemed very unpleasant for him, although I couldn't hear what he was hearing. The device emits ultrasonic waves, not electric shocks, and does not harm the dog's skin.

However, in a very short period of time, the material literally melted, and it stopped working properly because it was exposed to rain. The battery rusted, and I thought I needed to replace it. I couldn't find such a battery anywhere, so I had to order it online (product cost 0.62, paid around 7€ with shipping and cash on delivery), only to realize that the device itself was broken and didn't work again. Very cheap construction, like buying consumables