Square Tube 1.Grade:Q195 Q215 Q235 Q345 SS400 16Mn 20#, etc 2.Side Length:12-110mm 3.Wall Thickness:0.8-9mm ... 4.Length:5.8-12m Basic Information:Square tube is the tube that have ... tube. StandedAISI, ASTM, BS, DIN, GB, JIS, etcGradeMild Steel: Q195, Q215, Q235, SS400,20#, 45#, etcLow Alloy: Q345, 16Mn, Q390, ST52-3 ...