Not going metal just now as i understand that its the holidays.
It was advertised as a direct fit for the clio 172 and i asked if i needed any adapters for it and he said no its a direct bolt on jobby even came in a box that stated on the side for clio 172 which it is not so i would say regardless of the diameter size which most people wouldn't check if they were told it would bolt straight onto there car i would say i was sent an air filter that is wrong