It could use BOTH
Yes, it fits the 6" pneumatic plastic hub from AndyMark.
We lathed some excess off of ours to fit it into our shooter, I think the excess if for sprocket spacing. It lathes beautifully. Like 1334 we also scrapped the steel rims and inner tube, no pool noodle though. For a drive train I am sure you would want an inner tube.
Just a word of warning, the grey non marking wheels are just the black rubber wheels with a thin non marking layer on it, we noticed it starting to get rough after one shooter practice session. I am sure they would get torn up on concrete.
BTW last year if I recall correctly some teams didn't use a dropped center, and instead just adjusted the air in their wheels to get the desired results.