Sorry, I made some mistakes.
The roof base is not provided by “inno”.
That is other make and a commodity,
not for i3 only.
cf.
https://minkara.carview.co.jp/smart/userid/415925/car/3111497/12041030/parts.aspx
https://item.rakuten.co.jp/souplesse/souplesse-00295/
It looks hung on the rubber...