The Poly-Box is an odd piece of synthesizer technology. It's basically a small-remote keyboard controller for ancient analog synths, but with a twist. It takes control of your analog synthesizer and, even though they're monophonic, the Poly-Box will create polyphony by programmable chord memory presets. Designed for use via CV/Gate with other EML synths.

Here is how EML describes it:
"Poly-Box is a pitch following variable chord generator controlled by your synthesizer and Poly-Box's own keyboard with built-in memory. Poly-Box takes a single pitch from your synthesizer and creates two banks of pitch sources. Each pitch bank contains 13 simultaneously available pitch sources at precise semitone intervals - covering an entire chromatic octave. The pitch banks may be in the same or different octaves, and can cover the range from one above to three octaves below the synthesizer oscillator."

It has been used by Devo.