I have a rottweiler mix that was a crazy pulling machine. I bought this and it worked - for about a week. Once he got used to the feel, he went right back to pulling. He couldn't pull me off balance like before but he would have indentations around his muzzle when I would take the leader off, which I hated. The leader was put on properly, he's just stubborn. What I've found to work with him is a standard harness, short 4ft leash and at least 2 walks a day, one of which is at minimum 30 minutes. He still pulls a bit at the start of a walk because he's excited but it's manageable and he's not marked up when we get home.