Virtually all U.S. jails can be classified into three basic architectural/management categories: linear/intermittent surveillance, podular/remote surveillance, and podular/direct supervision. The linear/intermittent surveillance model is generally rectangular, with corridors leading to either single- or multiple-occupancy cells arranged at right angles with the corridors. Management style is typically reactive, with only intermittent surveillance of the inmate area. The podular/remote surveillance model has inmate housing areas divided into units or "pods" rarely exceeding 50 beds. The officer assigned to each pod is normally stationed inside a maximum security control station which overlooks the inmate areas. Communication with inmates is through intercom and telephone systems. The podular/direct supervision model has housing units divided into units of 30-50 individual rooms arranged around a common multipurpose area. The managing officer is assigned directly inside with the inmate population. The absence of physical barriers between inmates and staff places emphasis on effective interpersonal communications between them. Most direct supervision jails feature carpeting, commercial grade fixtures and furnishings, multiple television viewing areas, game tables, and exercise equipment. This model has proven to be the most cost-effective of the three in reducing inmate management problems and maintaining officer morale.