This is an electric octave mandolin, or a 5 string guitar. It has been converted from a Mitchell TD100.
The Mitchell TD100 was chosen for it's excellent build guitar for a short scale instrument. The angled heel contour is a feature you won't find on other instruments like this.
It has a 22.5 inch scale length, custom 5-saddle bridge, and a hand carved nut. This is a buttery smooth instrument that nearly has the range of a 7 string guitar in B standard.
This instrument features an all 5ths tuning (C-G-D-A-E). Meaning that you can take songs for mandolins, cellos, violins, and fiddles and play them without any adjustments or transpositions while also enjoying everything that comes with playing an electric guitar (bends, wah pedals, distortion, etc).
The "symmetrical" layout of the fretboard is perfect for free-flowing improvising, and it's massive sonic range means that it can do everything from mandolin barks to beefy breakdown chugs.
It's basically impossible to find 5 string electric octave mandolins, without using a private luthier.