The Viking CS05FTJWR030 is a 30-stage fan speed controller. It features a wide range of applications, ranging from circulation fans, inline fans, and centrifugal fans to roof vents and ventilation grills, in residential and commercial buildings. This fan speed controller is capable of controlling both AC and DC fans, allowing for reliable and efficient operation over a variety of environments. Furthermore, it is equipped with a built-in thermal overload protection, manual speed setting, and a removable enclosure for easy installation.