STRUCTURAL STEEL DRAWINGS
A typical example is TS6x4x1/4 where TS = Tube Steel, 6 and 4 are the actual width and depth in inches, and 1/4 is the wall thickness in inches. As of 2003, tube steel is now referred to as "Hollow Structural Section" (HSS) by the American Institute of Steel Construction. A typical designation is HSS6x4x1/4. 6.