The 250μm fibers are placed in a loose tube made of high modulus plastic, with water resistant filling compound filled in the tube. A layer of Corrugated steel tape is wrapped longitudinally on the loose tube.Water-blocking materials is applied between the Corrugated steel tape layer and the loose tube to keep the cable compact and watertight.Two strengthen steel wires are placed in both sides of the steel tape, and the outer sheath is made of polyethylene(PE). Characteristics:1.Slim, light, and easy to install;2.Stable control of the fiber remain length, insuring the tensile strength and temperature characteristics;3.Water-resistant and high strength loose tube;4.Special tube filling compound ensure a critical protection of the fibers; 5.Two strengthen steel wires ensure tensile strength;6.Central tube design minimize the side crush.