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 suppliers grade or material designation. Carbon tow or yarn, derived from a polyacrylonitrile precursor, with typical 400 ksi (2758 MPa) tensile strength and 33 Msi (228 GPa) tensile modulus for use in polyimide matrix structural composites or others which may be exposed to 315 degrees C (599 degrees F) thermal conditions in air and which require high tensile strength and moderate modulus of elasticity in tension