For telecommunications, cables can be installed in water, in air or underground. In the latter case, the cables might be direct buried or installed in ducts. The first is more common for copper balanc

S-Z Standard up to 312F or centrel tube structure up to 144 F;Mettallic, all-dielectric armored or unarmored;Steel wire or FRP for center strength member;The messenger wire can be steel wire or FRP;Go

S-Z stranded (up to 144F) or central tube structure (up to 96F);Air blown fibers (2-12 fibers), outer surface promoting low-friction;Aramid yarns for strength member;Light weight, small size, easy for