Found this gem accidentally - I was hoping against hope for a left handed fretless bass (very rare things are lefty fretless basses) in the, er, Left handed bass section, but actually it was hiding in plain sight in the Fretless section. Saw it, bought it, fitted it with flatwound strings and off I went. A slight tweak here and there and it performed very well indeed. I had borrowed a fretless Stringr ay forcomparison the JB-40 held its own remarkably well.
Highly recommended.