The ProLine® Standard Electric water heater is the reliable choice when you want to maximize hot water output and energy savings.The ENS-40 incorporates a 40-gallon (nominal) tank and 4,500 watts to deliver a first hour rating of 55 gallons at a Uniform Energy Factor of 0.92.Environmentally-friendly insulation and factory-installed heat trap nipples reduce heat loss for maximum energy savings.This ProLine® water heater features A. O. Smith's advanced tank protection, including a stainless steel CoreGard™ anode rod, Blue Diamond® glass lining, and DynaClean™ automatic sediment-cleaning — designed to help protect the tank from the corrosive effects of water and extend the life of the water heater. The ENS-40 includes a 6-year limited tank warranty.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.