GYTA [Outdoor Optical Cable for Communication with Metal Strengthening Member, Loose Sheath Strand Filling, Aluminum-Polyethylene Bonded Sheath] The structure of the optical cable is to insert a single-mode or multi-mode optical fiber into a high-modulus plastic and fill it with a waterproof compound. In the loose tube, the center of the cable core is a metal strength member. For some fiber optic cables, the metal center strength member is extruded with a layer of polyethylene. The loose tube (and filling rope) is twisted around the central strength member to form a compact and rounded cable core, and the gap in the cable core is filled with water-blocking compound and extruded with an aluminum-polyethylene adhesive sheath to form a cable.