American Standard® Gas Water Heater, Series: GSN, 40000 Btu/hr Heating, Natural Gas, 50 gal Tank, Spark Ignition, 3 in Vent, 38 gph Recovery, Energy Factor: 0.6, 3/4 in NPT Water Connection, 150 psi, Tall or Short: Tall, Ultra Low Nox: No, Aluminum Anode Rod/Steel Tank, 20-5/16 in Diameter