In "The Big Book of Pain", Donnelly and Diehl present an ingenious and diabolical iron torture boot. The configurable device completely encloses the naked foot. The roomy toe box is filled with iron spikes, teeth, and burs. A vertical plate behind the prisoner's heel fits into a grooved track and can be forced forward by turning a wheel. The steadily increasing pressure first forces the toes against the spikes, mangling their flesh and crushing their bones. Under continued inexorable pressure, the bones of the instep eventually give way until the arch of the foot is shattered. The heel bone is sufficiently powerful to withstand the torture, although the heel is not generously provided with afferent pain nociceptors.