Here is a vintage 1980 Electro Harmonix Mini-Synthesizer EH 0400 synth. Completely intact, including all original multi-colored rubber switch tips, this particular example is a very good simple-sounding analog monosynth, with the ability to slip it into a laptop protective case and transport it anywhere.
The membrane buttons/keys are well preserved, and have not been damaged. The plastic case exterior is also in perfect structural condition with no cracks. The internal speaker is intermittent, but it works fine with the aux. 1/8″ output jack.
This particular example is in very nice all original condition and features: a single analog VCO, a single Pulse waveform, an octave divider, a dedicated LFO for a Pulse-Width-Modulation effect, an analog filter, a sweep and phase rate with cutoff controls, as well as in/out of phase, resonance and filter switches.