GYTY53 [Outdoor Optical Cable for Communication with Metal Strengthening Member, Loose Layer Strand Filling, Polyethylene Inner Sheath, Longitudinal Corrugated Steel Tape Armor, Polyethylene Sheath In the loose tube made of plastic and filled with waterproof compound, the center of the cable core is a metal reinforcement. For some optical cables with a certain number of cores, the metal center reinforcement is extruded with a layer of polyethylene. The loose tube (and filler rope) is twisted around the central strength member to form a compact and rounded core, and the gap in the core is filled with a water-blocking compound and extruded with a polyethylene inner sheath. Double-sided plastic-coated plastic-coated steel tape is longitudinally wrapped and extruded into a polyethylene outer sheath to form a cable.