... ,low carbon mainly used in refrigeration,freezer etc. ISO9001,ISO14001 double wall copper coated steel tube1)material: bao steel strap, low carbon ... :3.18mm,4.0mm,4.76mm,6.35mm,8mm;3)wall thickness:0.5mm,0.6mm,0.65mm,0.70mm,1mm ... quality atttestation system;6)competitive price among the same area. double wall copper coated steel tube