The required number of optical fiber ribbons put together and covered by an extrusion of polyester materials, inside the tube which are filled with waterproof compound. The center of the cable core is a metal strength member. For optical cables of some fiber count, the metal strength member needs to be coated with a layer of PE. Loose tubes (and fillers) are stranded around the central strength member to form tight and round cable core. All the interstices of cable core are filled with water blocking compound. An laminated aluminum tape is applied longitudinally over the cable core, then covered by an extrusion of PE outer sheath.