Product developers characterize Helix 5-25 Micro-Rebar Concrete Reinforcement System as the only code approved material of its kind engineers can confidently specify as a replacement for primary structural reinforcing. Micro-Rebar are .5-mm diameter, 25-mm (1-in.) long fibers of twisted, high tensile (246 ksi), zinc-coated steel wire, dosed at 9 lb. to 70 lb. per cubic yard of concrete. Each pound of product has about 11,500 fibers.