What is the mechanical device used to restrain cattle?

It is called a Squeeze Chute. One cow or bull or steer or heifer enters the squeeze from a narrow alleyway or chute. Once in the squeeze the operator opens the head-gate to allow the head to slip through. Before the shoulders slip through the gate is pushed shut by the animal's shoulders and by the operator outside. If the animal is fighting the head gate the side panels of the squeeze squeeze together to calm the animal and further restrain it.