I had to see this one with my own eyes. Its a MIDI powered 2-voice synth with MIDI control programmable parameters, including some kind of analog filter. All about the size of a car key.
The Ploytec Pi L Squared is an extremely simple device, the power that MIDI supplies is enough to power the custom programmed chip to deliver 2 voices together with a healthy selection of programmable parameters. The only way to access if via MIDI control data. As I said the whole caboodle is powered over MIDI. Simple - MIDI in, audio out on a single phono connector.
Our demonstrator did have trouble finding the sounds, but here's a demo of the system from the Ploytec site.