Solar water heater with SOLAR KEYMARK,ISO,CE,SGS - Automatically controlled - Highly efficient insulation with polyurethane low pressure olar water heaterMaterial:Inner ... tube: AL/N coating, 47×1500/58×1800mmAccessories: water auto-feeding tank, electrical heaterLogo: OEM, color printing/ ... device or gas heater- Long service life, can be used as long as 15 years low pressure solar water heater