40000 Btu/hr Heating, Natural Gas, 40 gal Tank, Spark Ignition, 3 in Vent, 38 gph Recovery, Energy Factor: 0.64, 3/4 in NPT Water Connection, 150 psi, Tall or Short: Tall, Ultra Low Nox: Yes, Magnesium Anode Rod/Steel Tank, 20-5/16 in Dia (Price subject to change without notice. Check stock before order)