Powder coated 18 ga. steel front. Automatic reset thermal limit. Steel block fin element. Vane axial fan blade - 600 RPM / 175 CFM. Weight 22 lbs. Rough in dimensions - 14 3/16 in. wide x 19 15/16 in. high x 4 in. deep. Grill dimensions - 15 3/8 in. wide x 20 9/64 in. high. Units with dual wattage, factory wired to highest wattage. Watts selectable at time of installation. Factory wired to higher wattage.