This robust electric heater is powerful enough for ductable applications up to 50' with 14" outlets. The portable space heater is equipped with a dual output switch that allows you to choose between 40 or 42 kW and 102,400 or 136,500 BTU per hour outputs. The space heaters also feature a built-in thermostat that automatically turns the heater on/off. The power supply is direct wired, eliminating the need for expensive receptacles. Overheat protection will safely shut down the unit if the blower is restricted.