Non-pressurized solar water heater 1.low pressure with CE ,SK ,SRCC ,ISO901 2.competitive ... : 202, 304BA stainless steel or 1.5mm zinc coated plateVacuum tube: 58mm diameter, 1800mm length, coated by AL-N-ALInsulation layer ... ordersContact UsAny question please feel free to contact us! vacuum tube solar water heater