20mm insulation tube is 2 times thicker than normal insulation, which is much better on the thermal protection.Insulation is 3 layers close cell cross-linked  30 times PE foam. Inner layer is 120˚C resistant seamless extrusion tube. It has better anti condensation charactor due to smaller distance between insulation and copper tube. Outside embossed anti UV film could protect surface from scratching, deforming and aging so as to ensure its life time to over 8 years.Tube is 3 meters or 4 meters long with one end pre-expended. Copper tube is half annealed treated.