The OC-20G Poly Octave™ produces octaves for various combinations of strings (like the 5th and 6th strings) while leaving the other four strings unprocessed, making it the ultimate octave pedal for use with GK-ready guitars.
World’s first polyphonic octave pedal for use with GK-equipped guitars

Octaves can be assigned to different strings for simulated guitar/bass combos
Onboard electric and acoustic guitar simulations, plus Distortion effect
Accommodates playing chords while using octaves
Rugged, dual-pedal design with simple, knob-based controls

*Note that optional GK-2AH pickup or equivalent required for use.