American Standard® Gas Water Heater, Series: GSN, 40000 Btu/hr Heating, Natural Gas, 40 gal Tank, Spark Ignition, Atmospheric Vent, 3 in Vent, 38 gph at 90 deg F Rise Recovery, 0.61 Energy Factor, 3/4 in NPT Water Connection, 150 psi, Tall or Short: Tall, Ultra Low Nox: No, Glass Lined Steel, 18-5/16 in Dia x 59-1/8 in H