Has a three-way toggle switch that lets you switch from the sound of the 5E3 Woody (Tweed Fender Deluxe), High Power Twin (50's Fender Twin) and Master Volume Tchula (5E3 Woody and High Power Twin)
The volume is controlled by the first knob
The second knob is a second gain stage which emulates when you crank one of these vintage low wattage amplifiers