GYTA333 [Outdoor Optical Cable for Communication with Metal Strengthening Member, Loose-Sheet Stranded Filling Type, Aluminum-Polyethylene Bonded Inner Sheath, Double Layer Thin Round Steel Wire Armor, Polyethylene Sleeve It is put into a loose tube made of high-modulus plastic and filled with a waterproof compound. The center of the cable core is a metal reinforcing member. For some optical cables with a number of cores, the metal central reinforcing member is extruded with a layer of polyethylene. The loose tube (and filler rope) is twisted around the central strength member into a compact and rounded core, the inner gap of the cable core is filled with water blocking compound and the outer aluminum-polyethylene bonded inner sheath is extruded. The double-layer fine round steel wire armor is extruded into a polyethylene outer sheath to form a cable.