Many commercial and industrial buildings use steel tubing as structural components, such as rafters for roofs or as studs or posts. They can also be used in pole barns on farms or ranches as corner posts, wall studs or horizontal purlins. On trailers, they can be used to support the roof deck or as main structural components of the frame, and they can be welded together to create the frame for custom automobiles. They can also carry fluids, and galvanized versions are often found in water catchment systems. Finally, they can also be used as simple, lightweight signposts or light posts. They are durable, economical and long-lasting.