Might be a better question of what KIND of fiberglass...
Looks too fine to be a woven roving, doesnt look like biax or triaxial cloth, and not CSM.
And from the 2 pix, I cant determine a weight or how its reinforced.
I am not a fiberglass expert though.
Woodonglass
@ondarvr
Are you in Oregon? Unless you're less then an hour away, ask the seller to send you a 6in X 6in sample and/or more specifics.
Just remember if glass rolls have ever gotten wet or dirty, which can be hard to determine in a huge roll, it often affects how it accepts resins.