Seamless Steel Tube for truck trailer and heavy duty 1.ISO9001:2008 certified. 2.OEM is available. Seamless Steel Tube for truck trailer and heavy duty 1.Specification:121*20mm, 127*18mm, 127*20mm, 133*18mm, 140*16mmMaterial: 20#, 40# 16Mn, 27SiMn, 20Cr, 20Mn2