I'm not sure what you're seeing but, I made some for our Southwind.
Use
Reflectix insulation and cut it to fit the window.
I use the small suction cups with a hook attached to hang it on the window. Just put a small hole in the insulation and hang it on the suction cup. You can get the suction cups at any craft store or hardware store.
I originally tried stick on Velcro strips to mount the insulation. It worked for a couple days then the heat melted the glue on the strips and they slid off the window.
There are different brands and sizes of reflective insulation. Google bubble foil insulation.
Also, it has not caused any damage to my double pane windows.
I hope this helps.