Is your plastic screen door slide or "gizzy" cracked? This is commonly used on Airstream trailers from 1972-77 to help keep bugs out of the trailer while the main door is open.
This part is at least 8-1/2" x 7-1/4" overall, and about 1" deep. The flange has a width of approximately 1". Please measure to be sure your opening will work with this item.
The opening from one screen door to another is not always the same, so this item may have to be trimmed to fit your screen door.