This amazing and unique device has two modes of operation -- normal mode and oscillating mode. Normal mode boosts the input signal and you can add an extra layer of distortion with the LEAK knob. In oscillate mode, the pedal will begin to self-oscillate. In this mode, the FREQ and LEAK knobs work together to determine the type of oscillating sound. To top off all this madness, there is a STARVE switch which creates gated sputtering sounds in both modes. Extremely rare (only 16 made) and very well built.