Not sure what the story is behind this cool Bartell fretless, but the red, white, blue finish sure is awesome! Hopefully more info will be coming, especially the function of the oddly placed 4th knob (between the upper 2). The 3 knob arrangement and 2 screw neckplate are reminiscent of a few other Bartells found on this site.
Currently for sale at Lost Art Vintage Instruments.