This range of transformer controllers for single phase AC fans and motors provide energy saving speed control without the creation of additional motor noise which you get with most electronic controllers.
Vacuum impregnation further reduces electrical noise from the transformers.

Available for total load current of up to 7.5 amps,a rotary switch selects one of five different voltages.

The silent R-E Transformer controller produce no buzz on the fans, unlike electronic speed controllers, due to providing a smooth sine wave to the motor. Also lengthens fan life. Used for a truly silent fan setup.