Do you still have either of these bars on hand? Are they 18mm? Or 16mm? If either of them are 18mm, they may have been installed by whoever owned the car before you did? If either are 18mm, I might buy it off you at a reasonable price if you are interested. Of course, if they are standard 16mm, please disregard.
No, sorry, I turfed the old bars in a recent house move. But, I'm second guessing my measurements now anyway. Sorry chief.