The Marathon 50-Gallon Lifetime** Electric Water Heater features a seamless, blow-molded plastic tank which is impervious to rust and corrosion. Multiple layers of filament wound fiberglass give the tank unmatched strength and increased insulation to reduce energy consumption. Self cleaning action of bowl-shaped tank bottom and inlet tube helps fight sediment buildup. Lifetime limited warranty on tank and 6 year limited warranty on parts. Meets or exceed NAECA and UL requirements.