American Standard Gas Water Heater, Series: GSN, 40000 Btu/hr Heating, Natural Gas, 50 gal Tank, Spark Ignition, Atmospheric Vent, 3 in Vent, 38 gph at 90 deg F Rise Recovery, 0.65 Energy Factor, 3/4 in NPT Water Connection, 150 psi, Tall or Short: Tall, Ultra Low Nox: No, Glass Lined Steel, 20-5/16 in Dia x 57-3/4 in H