M.S. ERW Square & Rectangular Pipes are also known as Rectangular Hollow Sections (RHS) or Square Hollow Sections (SHS). These are used for general engineering and structural purposes. The manufacturing method is ERW (Electric Resistance Welded). However, in some cases,rectangular and square Seamless Pipes may also be used. https://www.kistindia.com/erw-rectangular-section-pipes-manufacturers-in-india