someone asked how it worked, i think somehow it is supposed to apply pressure across the chest and shoulder blades (if i remember correctly) when the dog tries to pull. and for whatever reason, the dog does not like it, so he doesnt pull. when he does try to pull, you are supposed to move the leash over to one side of you, and then the dog turns to you. when the dog is again beside you, you move the leash back to the normal position and keep walking.
i am telling you, when i used it for the first time, i was simply AMAZED by how instantly and fully it worked.