... and weathering resistance ,free of ,CFC , HCFC . Corrugated pipe(SUS304) :DN ID(mm) OD(mm) Bias(mm) Thickness(mm)12 12 ... with all solar heating system standard components..No soldering or welding required, make the installation easy and reliable ..Longer lifetime for ... Range :DN12 in lengths of 10 ,15,20,25,30 metersDN16 in lengths of 10 ,15,20,25,30 metersDN20 in lengths ...