I did a little research on this one since I heard that it is quite popular among the trainer.
And I indeed learned on various forums that this affordable is indeed good for training dogs.
Although I haven’t used it personally, I talked with a guy who trained a Pomeranian with it. He said that it works as a charm on a short range and the dog responded well to it. But the thing is, when he tried the same device on a large Rottweiler, the animal completely ignored it. He then tested it on some local stray dogs and most of them were annoyed by the device and quickly left the area.
Most of them backed away from trainer guy, but not every dog.
He says it’s a decent device, suitable to be used in your home or yard. You can train your dog with it, or just make that annoying neighbor’s’ dog stop barking. If you want to walk among the pack of mongrels hoping that this device will protect you, better reconsider your decision.