The cells are individual, semi-translucent, 12-sided prisms made out of some sort of crystalline material. They are contained in an enormous room in the Magic Council Headquarters, suspended in mid-air and are watched constantly by Surveillance Lacrima surrounding them.
These special cells are particularly suited to containing Mages, since the cell itself nullifies the use of any kind of Magic. However, it has been shown that this applies only to Caster Magic, as Holder Magic, such as Personification Magic, has been shown to work without trouble in the cell. However, since the prisoners would likely not be permitted any such items, this is possible only with outside help. Objects are able to phase into the cell from the outside, allowing sadistic guards such as Nadal to torture prisoners with their staffs.