This specification covers one type of continuous multifilament carbon fibers in the form of a tow or yarn (when twisted). The weight per unit length of the tow or yarn is governed by the filament count which is identified by the supplier's grade or material designation. Carbon tow or yarn, derived from a polyacrylonitrile precursor, with typical 220 ksi (1517 MPa) tensile strength and 75 Msi (517 GPa) tensile modulus for use in general purpose structural composites requiring very high modulus of elasticity and moderately high tensile strength
