square hollow section of best quality: Material: Q195, Q215, Q235, Q345B, X42, Gr. B square hollow section of best quality:hollow section, good quallity and attractive price 1.Item: hollow section2.Standard ... *400mm, WT: 0.6mm-12mm 1. Commodity specificationsSquare hollow section2. Process methodCold drown, high frequency welded3. MaterialQ195---Q2354. Size a. side length15mm ...