I build and mod guitars/basses for years. I think HB aimed at too low of a cost on this one. The part is so bad the savings just don't make sense at this point.
I've actually had some Harley Benton parts I've been happy with, such as chromed knobs and some tools. But this is not one of them. The Harley Benton bass nut is honestly an inferior quality useless part.
I think it's made with the idea of being a fully cut drop-in replacement for the HB jazz bass. Nonsense, every individual guitar is a little different, there is no silver bullet. Even string choice and setup changes everything. So this part is pretty much garbage.
A successor to this model could simply clone the TUSQ model.
So adding material on all edges, designed to be filed down to fit, and use from solid synthetic plastic. Some small holes on the underside are fine, but the whole thing being hollow does complicate things and makes it even less workable.
One compliment, the packaging appearance is attractive. Maybe raised expectations a bit too much however.