I checked. Willingen it was.
These were flags on the bracket that was a "jaw" that you slide on the glass (like the one we glue to the glass as part of window sliding/shifting mechanism). If you just slide it on the glass, it flies away at ca 90km/h. If you slide it and close the window against the roof - it stays.
It was not a bracket that you can fit in the hole for roof fixtures in the window frame, unfortunately.