Figure 8 fiber optic cable is constructed by placing a single-mode or multi-mode fiber into a loose sleeve made of high modulus plastic and filled with a water-blocking compound. The center of the core is a metal reinforcement core, and for some cores, a layer of polyethylene is extruded over the metal reinforcement core. The loose tubing (and filler rope) is twisted around the center reinforcement core to form acompact
and round core, with the gapsin the corefilled with a water-blocking filler. The cable core is wrapped longitudinally with steel-plastic composite tape and placed in parallel with the steel strand while squeezing the 8-letter sheath into the cable.