This is an MXR M78 Custom Badass '78 Distortion guitar effects pedal. It is a factory-modded pedal designed to emulate classic tube amp distortion tones. The pedal features three main control knobs: Output, Tone, and Distortion. A "Crunch" button allows users to boost the harmonic content for a thicker sound. The circuit is based on a hot-rodded classic design, providing over-the-top, soaring leads and rich, saturated rhythms.