Rectangular hollow section: Material: Q235, Q345, 20#, ST37, ST44, ST52, ASTM A53, ASTM A106 Rectangular hollow section:1.Item: square pipe2.Standard: GB ... , ASTM, BS, JIS, 3.Material: Q195, Q215, Q235, Q345B, X42, Gr. ... 3mm--13.5mm5. LengthMax 13 meters6. StandardGB/T6728-2002 or ASTM A5007. OthersWe can do special orders as per the customer ...