Interior shutters are typically divided into narrow units hinged accordion-style so that two or more units cover each side of a window opening when closed. Operable louvered shutters have louvers (or louvres in British usage), or slats, controlled by a tilt bar or rod to adjust the louver position and keep them in a uniform position, to control light, visibility and airflow. Shutters with operable louvers are described variously as traditional shutters, California shutters, or plantation shutters. Plantation shutters, typical of warmer climates like Florida, South Africa, the Mediterranean or Australia, typically have only two shutters per window and wide louver blades.