The structure is to insert a 9/125 μm single-mode fiber or a 50/125 μm, 62.5/125 μm multimode fiber (silicon dioxide) into a loose tube made of a high water-blocking material, and the loose tube is filled with a water blocking compound. The center of the core is a metal reinforcing core. For multi-core cables, the reinforcing core needs to be coated with a PE jacket. The loose tube and the filling rope twist the compact and round core around the center reinforcing core. The gap in the core is filled with a water blocking filler. The double-sided corrugated steel strip (PSP) is longitudinally wrapped and extruded into a polyethylene sheath to form a cable.
