Vintage Analogue Synthesizer in great condition, everything works as it should.

It sounds fantastic!   and lots of fun, Check out the videos on YouTube;

It's built into a sturdy carry case (you clip on the lid)

A quick search online told me this is a super rare synth

especially in good condition, here is some info:

The EKOsynth P15 from the Italian make EKO is a very rare pre-set-based synthesizer, circa 1979. The concept is typical of its time - it offers 15 pre-set sounds (hence the P15 moniker) that sound almost nothing like what they claim to emulate, with basic synthesizing capabilities when switched into "Manual" mode, housed in a rugged road-worthy case with built-in carrying handle and a latched cover.

The P15 is monophonic and totally analogue. Although it says "Digital System" on the front panel, this only refers to the underlying circuitry inside using some (at the time) modern integrated circuit chip technologies in place of traditional transistor based technology for a more stable result. The signal path is still entirely analogue from start to finish, and the result is very warm sounding.

The 15 preset sounds offer some unique flavours not often seen before, such as the Latin "Vihuela" and "Panpipe" instruments. However, most of the time users will prefer to use this synth in "Manual" mode which allows you to use the independent VCF and VCA sections. There is no oscillator section, however, when in "Manual" mode, the preset buttons can be used to select from the available wave shapes stored in the preset locations. These range from sawtooth and square waves to a mixture of others in various octaves. There does not, however, appear to be a sine wave and there is no noise generator.

The self resonating VCF (filter) has the typical Frequency Cutoff and Resonance controls. There are two basic envelopes - one for the VCA and the other for the VCF - each with Attack and Sustain controls. There is no Decay or Release. There is one LFO with sine or square waveforms that can modulate the VCF, VCA or VCO in varying amounts using the "Wah-wah", "Tremolo" and Vibrato "Intensity" sliders, respectively. The speed of the LFO can be adjusted to a rate of almost self-oscillation. Finally, there is also a "Glide" (portamento) option.

The attached YouTube videos will allow you to judge how the EKOsynth P15 sounds for yourself. But there is no denying that this is a rare and unique Italian take on the Preset-based synthesizer format of the late 1970's. It's easy to understand, can be a pleasure to play with (if in good condition) and with a construction of steel and wood wrapped in vinyl, is built like a tank!