when the max isn't really the max

So Barak, can you explain to me what a 'supermax' prison is? Pardon my ignorance, but I didn't know we had those. How is it diferent from a not-so-super, ordinary 'max' prison? How much more 'max' is it, and why? Do we, by any chance, have 'superdupermax' prisons that are even more 'max'? Just curious.

Yes, I realize Barak didn't make the term up, but it is pretty funny, or at least I think so.