This is a self-made effects pedal. As the name suggests, it's an effects pedal that can switch between a gain booster and a fuzz. The left knob is the shift knob; turning it above the blue mark activates the gain booster, and turning it below activates the fuzz. Fine gain adjustments are not possible. The right knob is the volume. When I boosted the gain of this pedal's boost mode with an overdrive, it created a cool distortion that can be used for rock music. The LED filament burned out due to the trial and error process, so the light doesn't work. It uses a 9V battery and comes with a snap connector that can be directly connected to a DC jack. The pedal itself does not run on battery power.