An exterior hurricane shutter or storm shutter is used to protect windows and doors in a building against the effects of high winds, rain, and flying objects during a hurricane, or as a security shutter over an opening. They can be made of a variety of materials such as fiberglass, steel, aluminum, wood or composite wood and can be installed in tracks to be quickly opened and closed manually or with motorized controls. The track-mounted storm shutters in America are of German design and are frequently of German manufacture. The walls of American houses are typically too thin to conceal the boxes that hold the shutters when open, so the boxes are visible on the exterior above the windows. There are also high-impact-resistant plastics that can be applied to new or existing wood shutters that provide hurricane protection.