The Head Crusher
A device for execution rather than torture. The victim's chin is placed on the lower bar, and the cap forced down by the screw.
First the teeth bite into the skull and smash the surrounding bone, then the eyes are forced out of their sockets, and finally the brain squirts through the fragmented skull.
Although nowadays no longer a means of capital punishment, head crushers are still used for interrogation in some parts of the world. The modern caps and chin rests are padded with soft materials so as to leave no mark on the victim.