relatively high level of security, usually close security or higher. Supermax prison facilities provide the highest level of prison security. These units hold those considered the most dangerous inmates, as well as inmates that have been deemed too high-profile or too great a national security risk for a normal prison. These include inmates who have committed assaults, murders, or other serious violations in less secure facilities, and inmates known to be or accused of being prison gang members. Most states have either a supermax section of a prison facility or an entire prison facility designated as a supermax. The United States Federal Bureau of Prisons operates a federal supermax, A.D.X. Florence, located in Florence, Colorado, also known as the "Alcatraz of the Rockies" and is widely considered to be perhaps the most secure prison in the United States. A.D.X. Florence has a standard supermax section where assaultive, violent, and gang-related inmates are kept under normal supermax conditions of 23-hour confinement and abridged amenities. A.D.X. Florence is considered to be of a security level above that of all other prisons in the United States, at least in the "ideological" ultramax part of it, which features permanent, 24-hour solitary confinement with rare human contacts or opportunity to earn better conditions through good behavior. In a maximum security prison or area (called high security in the federal system), all prisoners have individual cells with sliding doors controlled from a secure remote control station. Prisoners are allowed out of their cells one out of twenty four hours (one hour and 30 minutes for prisoners in California). When out of their cells, prisoners remain in the cell block or an exterior cage. Movement out of the cell block or "pod" is tightly restricted using restraints and escorts by correctional officers. Under close security, prisoners usually have one- or two-person cells operated from a remote control station. Each cell has its own toilet and sink. Inmates may leave their cells for work assignments or correctional programs and otherwise may be allowed in a common area in the cellblock or an exercise yard. The fences are generally double fences with watchtowers housing armed guards, plus often a third, lethal-current electric fence in the middle. Prisoners that fall into the medium security group may sleep in cells, but share them two and two, and use bunk beds with lockers to store their possessions. Depending upon the facility, each