Electrical pipe, also called thin-wall conduit, that may be used for both concealed and exposed areas. It is the most common type of raceway used in single-family and low-rise residential and commercial buildings.
electrical metallic tubing (Wikipedia)
An electrical conduit is a tube used to protect and route electrical wiring in a building or structure. Electrical conduit may be made of metal, plastic, fiber, or fired clay. Most conduit is rigid, but flexible conduit is used for some purposes.
Conduit is generally installed by electricians at the site of installation of electrical equipment. Its use, form, and installation details are often specified by wiring regulations, such as the US National Electrical Code (NEC) and other building codes.