This is a really interesting one. Our sources suggest only 300 were made and who knows how many still exist? It's apparently the first digital musical instrument, though it's more than just an instrument - it's a compositional aid. There are 8 musical pattern control sliders, each with 40 positions. They are broken down into 2 sets - interval and theme. You use the faders to create repeating melodies played by the built in synthesized sound. The interval faders define the pitches and the theme faders cause variations of those melodies. Every time you move a fader position it alters your pattern. This is an amazing piece of equipment as it can take an initially simple pattern and turn it into a complex musical passage. The tone generator is a simple but fat square wave and it's got a built in speaker and faders to control tempo, pitch, fine tune, volume. There are switches for off, on, start, auto, hold, step, rest and external sync. There are also connectors on the bottom to interface it with other Muses and probably can be interfaced with other gear but would =need modification for this - please research compatability in advance if this is your intention. Best of all, its really retro futuristic looking! It looks like something out of Woody Allen's movie Sleeper! It's prism shaped and, on the right hand side, has a vertical row of green and blue lights which shoot from top to bottom as the sequence plays (the light pattern corresponds to the sequencer pattern). It's pretty hypnotic. This is truly a rare and unique piece and a great creative tool or collectors item. You don't have to have any musical ability at all to play the muse. This might even be something for the vintage furniture or gadget collector as well.