We got an instant response from our dog when using the collar (noise/vibration – we haven't needed to use the shock function) and it completely transformed our lives, as we didn't need to keep thinking about how to manage her when in video meetings etc. It's cheap, the battery lasts for ages, and it works. Until it doesn't. Our one suddenly stopped responding to the dog barking, and no matter what sensitivity level, it still doesn't work. But, it does work when you blow on the back of it (how you test the settings). Anyway, given it's a 10th the cost of other collars we looked at, it's still not bad, and I will buy a replacement.