Many different forms of Torture chairs were used during the dark ages. They were usually made of heavy wood to withstand the struggling of the victim. The surface of the chair was covered with spikes or blades designed to cut through the skin while keeping the victim alive. In addition to the spikes, some chairs also had over sized attachments designed to penetrate anus and/or vagina. Later chairs also sometimes features a metal base under the seat that could be used to heat the spikes.
The victim was strapped into the chair at the ankles and wrists and usually had an additional strap around the chest. Then the chastiser would often use branding irons or whips to cause the victim to jerk, increasing the effect of the spikes.
Today, several variants of these chairs are available to the BDSM community. The metal spikes have generally been replaced by softer and easier to clean plastic spikes. This prevents the spikes from actually penetrating the skin while still creating a great deal of discomfort. Some chairs also contain metal contacts that can be attached to tens units or violet wands for electric play with the bound person.