Fantastic collar, fantastic invention, easy to use and makes me feel at ease when taking my dog out. She can be quite nervous and has had a few dodgy encounters, but nothing too serious, and when you’re too far to stop anything, it’s scary. I did try this collar and I did set it off when a dog started sniffing round her, but luckily nothing happened, though I did feel more at ease with her having the Dogfender Collar on. Brilliant invention!!!