Square pipe is often used for architecture.

It is painted with red rust paint. Thickness 0.09 in (2.3 mm) x A 3.9 in (100 mm) x B side 3.9 in (100 mm) Length L 19.7 in (500 mm) Material: Square steel tube for general structure STKR400 (JIS G 3466) Leveling point 245N/mm2 or more Tensile strength 40 or less