Rheem 22V40F1 Natural Gas Water Heater, 40 Gallon 40 gallon - natural gas Self - Cleaning - Everkleen patented system fights sediment build-up High altitude compliant 6 year tank and parts warranty from Rheem Meets Low Nitr0gen Oxide emission standards. (Not compliant for emissions in some Cities/Counties in California - please check your local codes before ordering.)