The Maestro Parametric Filter MPF is a truly unique vintage filter pedal. Made around 1977, the body of the pedal is stepped on to turn on and off the effect. There is a large knob on the top of the pedal that selects 5 different filter modes. The dial on the right controls the frequency you want to cut or boost. The other dial on the left controls the amount of cut or boost. Can be used for a parametric equalizer or a fizzy fuzz! Powered by a single 9-volt battery.