1/2" Chopped Fiberglass Fibers / Strands for Concrete Countertops, Plaster, Resins, Crack Reinforcement, GFRC - 12oz Bag VBP BRAND 1/2" Fibers to strenghten any setting mix. 12oz Bag. Reinforce any mix to strenthen against cracking, warping. Add one pack or more per cubic yard. Each strand is made of multiple strands. Use in GFRC countertops, plasters, stucco bases, resins.