Hi,
my Kenko Pr 300 is black colored.
It's type says "N-AF 1.4x TELEPLUS PRO 300" after 2 cutouts it says in gold colour "DGX".
The box looked the same, I think. Don't have it anymore.
It multiplies my lenses with 1.4.
So my 24-120 mm f4 lens at 120 mm gets 168 mm, the EXIF says 170 mm. It f number is 5.6 al the lenghts.
My 70-200 f4 lens at 200 mm gets 280 mm, also 280 mm in EXIF and also f5.6 whole range.
With the cam (D750) in 1.2x mode 336 mm (I don't use DX mode).
I don't feel a difference in AF speed and its sharpness stays as without.
It makes my walkaround lens a super walkaround lens and my 70-200 a good tele.
I'm happy with it.
Ad B