Yep. What the others are saying. I looked at it in Meshlab and it appears that one fin is slightly shorter than the rest, the one opposite this one does not touch the cylinder, and the two perpendicular to those are a tad off center. All 4 of these fins seem to have intersecting faces with the cylinder and the base they sit on. I don't know the specs of your printer, but if this were ever to be printed on something other than a filament type, it would also get rejected due to wall thickness issues and what they call "non-manifold" or watertight issues. You may have to close off the bottom of the lower cylinder if its not supposed to be hollow, or at the very least thicken up the width. Biggest issue like I said though is all the intersecting faces. The software in your printer may be able to ignore those, but the one fin standing by itself has no real support and may not print properly.