unless the horse wants to run off then you can refer to the pictures above to see what happens. If you can control the horses nose you can control the whole body.
What I am saying is not everyone needs to run out and buy special equipment for every problem. In this case, a chain would work too. Run the chain from the ring on the opposite jowl piece, through the side ring, over the nose and through the ring on the near side. The head will stay down and the nose can be tipped in. But chains are not for people who can't give and take pressure instantly.