... polyurethane foam thickness 55mm ; Holes:4 holes,water inlet and outlet,electrical heater,vent. 2 ... steel thickness 1.2mm,1.5mm. Assitant water tank,electrical heating element,controller,reflector is optional ... Water Heater, Solar Hot water, Solar Water Heating, Solar Heaters, Solar Water Heater, Solar Hot water, Solar Water Heating, Solar Heaters, Solar Water Heater, Solar Hot water, Solar Water ...