International Systems Inc., Mobile, Ala., uses assembly-line production techniques to produce complete, permanent concrete jail cells, quickly and inexpensively. ISI produces 2,100 modules a year. They construct modules using hot-water-injected concrete with a lightweight mix design, and a design strength of more than 5000 psi. ISI completely finishes each cell. Every module contains everything it needs to be used immediately--from doors to drinking fountains. Each cell has three elements: a floor slab, a ceiling slab, and four walls poured monolithically. The module's walls are cast simultaneously around a steel framework, inside a casting machine. The cells are coated with a substance that causes the concrete to cure to the unpainted, outer side of the module, allowing painting within 7 days. On the walls of the cell, ISI uses a two-component, heavy-duty epoxy coating to provide abrasion, bacterial, chemical, and stain resistance. On the floors, a two-component, low-VOC acrylic resin coating designed to resist corrosion and abrasion is used. Completed modules are transported to the construction site, lifted by a heavy crane and arranged directly on a foundation or stacked according to design. The facilities are typically ready for occupancy within a few weeks.