Kawai Macro Controller

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via this auction

"This is an incredibly rare unit made for the Kawai K5000 series, and is essential for having some hands on knob control to edit parameters on the K5000R. It's in MINT condition and fully functional."

I believe this works with the K5000W keyboard synth as well. The K5000S has the knob section on board but lacks the workstation aspect of the K5000W.

Pics of all sides below. Note the connections are on the right rather than the back of the unit and appear to be standard MIDI vs. a proprietary system. Some details on the MIDI here.