Direct buried steel tape armoured cable is available in fiber optic, loose tube, Flextube, unitube, and spiral space product families. Uses steel tape armoring for maximum crush resistance. The optical fiber itself is an insulator and protects against power transmission line and lightning induction, external noise and cross-talk. Typically OPGW cables containsingle-mode optical fibers with low transmission loss, allowing long distance transmission at high speeds. The outer appearance of OPGW is similar to ACSR cable usually used for shield wires.