Love The Drive BMW Windstop 3 series (E46) 323, 325, 330, M3 2000 to 2006 - Manual (Page 3)

Now on the drivers
side, while still
holding on to the
wind deflector,
lower it so the
barrel bolt is in line
with the hole in the
trim panel.
Complete the installation by closing the lid that
covers your top completely. The rear brackets will
be locked into place by lid and your wind deflector
will sit securely in place.
Then slide the plastic barrel bolt into the
hole and turn the plastic handle
downwards to lock it into position.
Then lower the wind deflector into the rear seat area so it is flat.
The rear brackets will sit on the lip that is below the lid that covers
your convertible top. You may need to adjust the rear brackets
slightly inward to fit your BMW as each car is a little bit different.