One of the most notorious Medieval torture devices is the thumbscrew. It was operated by way of three upright metal poles. Along these metal poles sat a vertical slab of either metal or wood, which could be slid up or down. The operation of the device was simple: the victim would have their fingers forced into a gap just beneath the slab, and the torturer would slowly lower it, crushing the victim’s fingers one by one. It was very efficient, as it was completely non-fatal, cheap to produce and yet frighteningly effective. Regular use was made of the device during inquisitions into heresy, and it was particularly popular among the interrogators for its noted ability to draw out forced confessions.