Yes to fiberglass and youll TN need to cut to size. But they work just fine.
my DB or at least the first had carbon fiber rods. It's a Tru Double Bull. My sevond has the aluminum rods.
both have zipper doors.
even had the zipper repaired once.
Now at the end of the yr I set the blind up and spray my fabric inside with flat black.
and I hand sew any years.
JW