4-string · bolt-on
passive electronics system 4-string, per the product category Thomann files this model under (Thomann is Harley Benton's own house brand).
| Construction | bolt-on |
| Strings | 4 |
| Body | Poplar |
| Neck | Maple |
| Fingerboard | Laurel |
| Neck Pickup | JB-style single-coils |
| Controls | 2 volume and 1 tone |
Artists documented playing the Harley Benton JB-20 MB: Marti Fischer.