Pipeline video inspection is a form of telepresence used to visually inspect the interiors of pipelines. A common application is to determine the condition of small diameter sewer lines and household connection pipes. Older sewer lines of small diameter, typically 6-inch (150 mm), are made by the union of a number of short 3 feet (0.91 m) sections. The pipe segments may be made of cast iron, with 12 feet (3.7 m) to 20 feet (6.1 m) sections, but are more often made of vitrified clay pipe (VCP), a ceramic material, in 3 feet (0.91 m), 4 feet (1.2 m) & 6 feet (1.8 m) sections.