The structure of gyfxty optical cable is to insert 250 micron optical fiber into a loose tube made of high modulus material, and the loose tube is filled with waterproof compound. The center of the cable core is a piece of fiberglass reinforced plastic (FRP). The loose tube (and filler) is twisted around the central strengthening core into a compact and round cable core. The gaps in the cable core are filled with water-blocking filler. A layer of polyethylene sheath is extruded outside the cable core to form a cable, which is widely used in pipelines and overhead operations.