The ProLine® 40-Gallon Atmospheric Vent Tall Natural Gas Water Heater is designed to deliver an economical performance that can lower your energy bills and also provide long-lasting value. Featuring a 40-gallon (nominal) tank and the GCR-40L Standard Vent delivers a first hour rating of 80 gallons and a recovery rate of 42 gallons per hour. It carries a 6-year limited tank warranty, and meets Low NOx emission requirements. Environmentally-friendly insulation and factory-installed heat trap nipples reduce heat loss for maximum energy savings. This ProLine® water heater is designed with A. O. Smith's superior commercial-grade tank protection. Advanced tank features include stainless steel CoreGard™ anode rod, Blue Diamond® glass lining and DynaClean™ automatic sediment-cleaning system, all designed to help protect the tank from the corrosive effects of water and extend the life of the water heater. A. O. Smith’s ProLine® water heaters are residential products built to commercial-grade standards and are only available for purchase through professional wholesalers and contractors.