Carbon Fiber Tube - Unidirectional - 1/16" ID x 1/8" OD x 4 ft. LongCarbon Fiber Tube Unidirectional 1 16" ID x 1 8" OD x 4 ft. Long Model #: WBB2320359 MPN #: BULK CT CF 1 Unidirectional carbon fiber has its fibers running in a single parallel direction so it is ideal for applications where front to back strength is important. Long, tubular structures that move in a forward and reverse direction, such as rockets, airplanes, boats, and bicycles, all use unidirectional carbon fiber as reinforcement. Weights &