Each element is in a tube within the cable (not a blown fibre tube) The cable elements start with the red tube and are counted around the cable to the green tube. Active elements are in white tubes and yellow fillers or dummies are laid in the cable to fill it out depending on how many fibres and units exists – can be up to 276 fibres or 23 elements for external cable and 144 fibres or 12 elements for internal. The cable has a central strength member normally made from fiberglass or plastic. There is also a copper conductor in external cables.