... the excellent performance,has been passed CE,ISO9001 Certificate.And solar kemark,SRCC are under apply 1.inner tank: SUS ... plastic spraying4.Meterial of insulation:polyurthane,it can keep the water temperature last for 72 hours5.vaccum tube: high borosilicate ... :15 years7.Freeze protection:-10°C,wind stress:180km/h without damage,Hair resistance:25-35mm(dianeter) Non-pressurized Solar Water Heater