When “No Pull” Assistance is needed, ThunderLeash quickly and easily wraps around your dog’s torso using the patent-pending hardware design. When your dog pulls, ThunderLeash will apply safe pressure to the torso. This gentle, consistent feedback lets your dog know to stop pulling. No need for a separate harness or headcollar. Professional dog trainer recommended. When Pulling is NOT a problem, just clip onto your dog’s collar like any standard leash.