Back in the day (the mid 1980s), my friend Paul had one of these - a Roland G-77 Bass Synth - complete (unlike the one for sale here) with the hefty synth unit that sat on the floor and which this thing plugged into. We nicknamed it, the Dalek's Handbag, and Paul found a hologram of a dalek which he stuck on the front between the two jazz bass pickups.
This of course was the bass companion model to the Roland G-707 guitar synth, although the bass was superior in a couple of ways. It had individual analogue to digital converters for each string unlike the guitar which had one for all the strings and so the tracking was much better, and it had a slightly more sensibly-designed shape so that you could actually balance it on your knee when playing it sitting down.
When Paul sold the bass, somehow I ended up with the hard case, which I used for many years for my bass that I had assembled myself from parts bought from Brandoni guitars.