I hired one of these from my local pet shop for my daughter's lurcher. He is very nervous and barks if left alone, or in new company. Within a couple of days he was a changed dog. He was calmer and rarely barked, even at strangers. Not only is my daughter delighted but the neighbours are too!! I therefore bought one for my daughter and she rarely has to use it, showing the collar to him seems to have the desired effect. We are all delighted, and I would have no trouble recommending this to anyone with a barking dog. Expensive but great.
This is quite expensive and you might wonder whether it is worth the money. I bought one recently for my new 5 year old rescue dog who barked and howled incessantly when left, much to the distress of my retired but usually very tolerant neighbours. It worked instantly and has meant we can keep our much-loved new pet. Highly recommended.