The finned armoured heating elements are suitable for several industrial applications, such as heating of air and gases at a controlled temperature or keeping indoor spaces at a specific temperature. They are installed in ventilation ducts or air-conditioning systems for the direct heating of airflow. The finned surface of the heaters increase their thermal exchange coefficient. Electrical duct heaters are made up of a flanged duct of known size and one or two terminal blocks following the IP protection degree. Ducts can be square , rectangular or circular sections, with or without finned elements according to application and temperature.