I was very reluctant to use a bark collar on our rescue Kelpie X Whippet and have been trying for over 12 months to train her to control her barking. But there are a couple of triggers that cause her to react with frantic barking and all my efforts at training had little effect. The bark collar was very effective from the moment I put it on her, and thankfully, it didn't cause her any stress or harm at all. It achieved in a few hours what would have taken me many months (or more). I will continue to use the collar in conjunction with training, but I am sure the need for this will become less frequent over the coming weeks. Also, thank you for the great advice you provided over the phone when I first contacted you, and for the ‘renting’ option which you offer. This is a great service. It enabled me to appreciate the effectiveness of the collar before I bought it.