Circulation Heater, 18,000 W Watts, Sheath Material Incoloy(R) 800, Screw Plug Material Stainless Steel, Watt Density 48 W/sq in, Flange Size 3 in, Heater Voltage 480V AC, 3 Phase, Overall Length 58 in, Control Range 60 Degrees to 250 Degrees F, Enclosure Type NEMA 1, Min. Immersion Depth 57 1/8 in, Flange Material Steel, Special Information Optimum Operating Efficiency and Performance, Self-Contained Heating Units, For Use With Air, Water, Includes Tank Mounted Double Pole Thermostat