This Can-Fan variable voltage speed controller is for all 120 volt, 60 Hz. fans with less than 7.5 amps drawn. This product provides smooth sinusoidal wave, so there is no growl at running speed. This unit is a MUST 12" & 14" Max-Fans. This high quality Auto-Transformer type control is the answer for mastery over your airflow. By providing a smooth sinusoidal wave to your fan it eliminates any motor hum and unnecessary strain on the motor. Can Fan Speed Controller Specs: The Can-Trol Speed Controller Auto-Transformer Built in Amp meter Grounded Receptacle Illuminating ON/OFF switch