via this auction

And, of course, it produces great TB-303-esque tones and slides that you can access via a MIDI keyboard or MIDI sequencer. This Mark III version includes a Korg MS-20 style ring modulator in addition to the usual TB-303 saw and square waves. The filter sounds amazing. It's a very solidly built 1U rack unit with probably the most sturdy knobs I've ever gotten my hands on.
Ultimately, this is a wonderful unit if your starting point is MIDI (DAW, sequencer, etc.) and you want to access great analog sounds, both with this unit itself and with vintage synths that aren't already MIDI controllable."