The Helios TSW 1.5 is a speed controller transformer that regulates the speed of one or multiple fans by reducing voltage in five selectable steps. Equipped with an on/off switch, it is designed for surface mounting in indoor environments. The unit’s housing provides IP20 protection, safeguarding against solid objects. Voltage options include 0, 80, 130, 170, and 230 volts, and it operates at 50/60 Hz frequency, ensuring dependable fan speed control.