The Gentle leader was invented by UK pet behaviourist Peter Neville was it not?

The Late John Fisher also devised a similar one that he called a col-leash but I don't know where you can get those now he has passed on.
I know the col-leash was adjustable to grow with the dog so you could use it on them as a puppy and just adjust it as they grew so no buying seperate collars and leads for different stages of growth.

Both are designed to prevent the dog from learning to pull partly my making it so that there is nothing to pull against.