The Alliance G, a porcelain (glass) lined indirect water heater is available in four sizes: 40, 50, 79, and 100 gal. Each tank is surrounded by CFC-free foam insulation, and the 40 and 50 gal tanks are wrapped in a steel jacket, while the 779 and 100 gal tanks are wrapped in a durable plastic jacket. Each size includes an aquastat, clean out inspection plate, and a sacrificial anode rod.