Thunder Leash - No Pull Leash for Quick Simple Positive Training Large Uses gentle torso pressure to discourage pulling: ThunderLeash in the harness configuration puts a gentle pressure on the dog's torso when they pull to deter the dog from continuing to pull. Simple and clever!: The specialty hardware designed for the Thunderleash instantly converts from a standard leash into a no-pull harness. Strong and Durable: Made of very durable hardware and strong black nylon featuring a blue ribbon Thunderleash logo and a padded handle. Safety first!: The ThunderLeash in no pull harness configuration has a safety buckle which does not allow it to over-tighten on your dog. In addition, it does not put any pressure on the joints or turn the dog to the side.