Advertised measurements are accurate - 30.3mm for the front and 25.36mm for the rear.
Rear bar is ~10lbs, front bar is ~16lbs - not sure how to tell if they are hollow, I'm sure as hell not cutting one in half!
The bars came with the paint chipped in a few spots, not a big deal but it definitely happened pre-shipping (they were packed well). The middle brackets are welded on (not crimped) which I believe is the same for other sway bars as well? Pics are attached