I had tried gazillions of harness and always my mid-sized mixed breed would refuse to walk, look miserable and anxiously lick her lips. When I put this one on, she accepted it. Once I adjusted it to fit - she trotted off happily and seemed to forget she was wearing it. She is an 12 y.o. 40lb chow/dachshund-cross with a narrow deep chest. She seemed to hate the way other halters constricted her shoulders. - This one is a good fit. And thank you to the Clean Run staff who helped me chose and size the harness, all accomplished on-line.