It attaches with six pads that glue down to the window. The two top-center pads are hinged to allow for the entire assembly to lift up for cleaning the window. There are two top outer ones that just sort of hold the corners down, but do not interfere with the hinging action. Finally, there are two lower pads that have catches on them. This allows you to lock the louvers in place as well as unlock them to swing the louvers up so you can clean the window.
The pads have 3M adhesive tape on them and they are really very secure. I have absolutely zero concerns about the pads ever coming free on their own. I can take some detailed photos of all of this and post them if it would be useful to anyone. Just say the word.