... 4mm/ 0.5mm / 0.6mm, 304-2B(food-level stainless steel)Material of outer water tank: 0.31mm, 0.4mm, 0 ... .5mm stainless steel,or colorful armor plate, or PVDF Heat preservation: 55mm, ... stainless steel or galvanized steel plate or alumminum alloy.Angle of bracket: 25°, 38°, 45°Reflector: stainless steel sheet or stripDaily efficiency: above50%Optional electrical heater ...