the doors or windows, carving away the walls, or breaking away the vent. Containment penetration Containment penetration involves breaking down or slipping through the physical containment of the prison, including that of the cell itself or the surrounding complex. Methods include the destruction of the cell or compound walls, squeezing through tight spaces, or entering off-limits areas. Prisoners often destroy their containment with homemade tools, smuggled objects, or other contraband. Most prisons are contained on the outside by one or more fences, often topped with barbed wire or razor wire. Escapees manage to scale these fences successfully or cut holes in the fences, damaging them. These fences are also watched by one or more guards from a tower, but escapees manage to pass the fence when the guard is turned away, unable to see in the dark, or sleeping on the job. Outside the fences is often a perimeter patrol conducted by an officer in a vehicle, which stands as the final line of defense. Escapees manage to evade this by studying the length of time between passes, waiting until it is on the other side, or using the cover of darkness. An uncommon method that has been used at times involves the digging of a tunnel under the facility that exits outside the facility. Physical force Physical force involves attacking guards with blunt force, homemade weapons, smuggled weapons, or weapons stolen from overpowered guards. Some escapes involve one or more inmates taking over an entire unit or section of the prison, subduing guards, and stealing weapons or other objects they can use to their advantage. Deception Deception may involve fooling one or more guards into believing the prisoner is authorized to depart prison grounds for a legitimate reason, or the prisoner disguising himself or herself as a worker or civilian who can exit prison grounds without arousing suspicion, or the creation of a ruse to mislead guards. In some escapes, inmates construct makeshift dummies to make guards believe they are in their cells, usually in bed, when they are not. This enables the inmate to gain a head start from the prison before guards discover they are actually missing. Such dummies are typically constructed quite crudely, often using the inmate's or another's hair, shoes, and miscellaneous materials for stuffing, hidden under a blanket to give the appearance a body is present. Exploitation of weaknesses Finding holes in the security