Product Detail;-Supreme Solar 220 ltr glass-lined coated, is far superior in technology to protect the tank from harsh water conditions.  Since the solar tanks are the ones that will get damaged due to bad water conditions, its advisable to buy this model.Glass lining is a material made by fusing powdered glass to the inner surface of the metal tank by firing between 850 C to 870 C. Molecular interaction, resulting in a coating that melts, flows, and then harden to a smooth, durable glass coating on the metal surface. So that glass and steel can not be separated from each other. Glass lining provides superior longevity to a hot water tank. In certain areas, stainless steel tanks tend to fail more rapidly than glass-lined tanks due to chlorides in the water, and Hence This solar water heater is much advisable than the normal stainless steel or copper solar tanks.