18 Tubes,150 L Evacuated Solar Water Heater 1.SRCC,Solar Keymark.SGS, 2.100000Btu/ ... and workmanship. 2.15 years for vacuum tube 18 Tubes,150 L Evacuated Solar Water HeaterSolar hot water specification: 1. Inner tank ... .4mm-0.6mm thickness SUS 304-2B Stainless steel 18 Tubes,150 L Evacuated Solar Water Heater