Straight rails for use on domestic staircases are usually made from extruded aluminium or steel and come in various cross-sectional shapes. These rails may, typically, weigh over 30 kg, depending on the length. In most applications they are attached to the steps with metal brackets (sometimes called “cleats”). If a rail crosses a doorway at the bottom of the stairs or causes an obstruction a hinge can be fitted so the end of the rail can be folded back out of the way when not in use. Curved rails are made from materials such as steel or aluminium and come in various cross-sectional shapes according to the designer. Individual designs vary a lot and probably the key criterion is to make the curves with the smallest radius possible so they will wrap tightly around objects such as newel posts. The sections of curved rails usually packaged well to prevent damage in transit and are unwrapped and assembled on site. Rails for wheelchair platform stairlifts may be secured to walls in addition to the step fixings.