The structure of the GYTC8S optical cable involves placing 250μm optical fibers into loose tubes made of a high-modulus material, which are filled with a water-resistant compound. At the center of the cable core is a metal strength member, around which the loose tubes (and filler rods) are stranded to form a compact, circular cable core. The cable core is longitudinally covered with a plastic-coated aluminum tape (APL), then integrated with steel stranded wires into a figure-8 polyethylene sheath.