1/2" Chopped Fiberglass Fibers / Strands for Concrete Countertops, Plaster, Resins, Crack Reinforcement, GFRC - 5lb Box VBP Brand 1/2" Fibers to strenghten any setting mix. Reinforce any setting mix to strenthen against cracking, warping. Add one pound or more per cubic yard. Each strand is made of multiple strands. Use in GFRC countertops, plasters, stucco bases, resins.