One more perfect pencil.
It looks like the original green plastic version has been updated.
The newer version has some minor cosmetic differences and a major functional difference – the pencil is now held in the extender by friction or tension, rather than a screw on mechanism.
It is also offered in Japan in a black version, shown in the photos here. The black version comes with a round pencil, black with black dyed wood.
Something else I hadn’t noticed is that the Castell 9000 pencils supplied with the green version (and in the refills) are marked in silver, while the general Castell 9000 pencil has gold markings.
Some side ribbing seems to be the main surface difference.
It is hard to say this authoritatively, but I sense prices have been reduced in most markets compared with the original.