This is a 1970s Hohner bass ad featuring model numbers XK-250 (Jet Black finish) and XK-251 (Natural Blond finish).  The basses pictured in the ad are versions that Hohner had made in Germany after the Bartell factory closed.  The pickups are completely different from Bartell models with both pickups featuring 3-point adjustment while the bridge pickup has offset polepieces, looking more like a P-bass pickup under a humbucker-sized cover.  The knobs are black skirted knobs with numbers.  You can also see that the bridge pickup has moved closer to the bridge and is now below the neck adjustment screw.  I have seen a couple of these on ebay and in another collector's collection so they're definitely around.

1970s Hohner bass ad