THE WORLD’S FIRST POLYPHONIC OCTAVE PEDAL.
The BOSS OC-3 Super Octave gives guitarists high-quality octave effects with a single stomp. Three modes are provided, including a new Polyphonic Octave mode, a Drive mode with distortion, and the original OC-2 mode. The versatile OC-3 also has separate inputs for both guitar and bass.
More info at http://www.bossus.com/products/oc-3/