... /rectangular /square pipes Specifications:1) Round pipes-Outside diameter (unit: mm)8,9.5,11,12,12.7,14.5 ... ,133,141,159,2192) Square pipe-Outside diameter (unit: mm)10×10,12×12,15×15,17×17,18×18,19× ... 70,80×803) Rectangular pipes: Outside dimensions (mm)20×10,23×11,24×12,25×13,30×30,36×36 ... .7) Tolerance: a) Outside diameter: ±0.15mm, b) Thickness: ±10% of wall thickness, c) Length: ±4.5-0mm8) Outer size ...