• Central Strength Member (CSM)Material:

Fiber Reinforced Plastic (FRP) rod.

Function: Positioned at the exact geometric center, it acts as the primary load-bearing backbone. It resists axial tension during pulling and prevents the cable from buckling or shrinking under extreme temperature changes. Because it is plastic-fiber based, it provides complete electrical isolation.

• Optical Fibers

Material: Single-mode (typically G.652.D) or multimode glass cores.

Function: The actual data transmission medium. They are placed loosely within the buffer tubes with excess length to ensure they suffer no physical strain when the outer cable stretches under tension.

• Loose Buffer Tubes & Fillers

Material: High-modulus plastic (usually PBT - Polybutylene Terephthalate).

Function: Protects the delicate glass fibers from external lateral crush forces. If the fiber count of the cable is low, solid plastic fillers (dummy tubes) are used to maintain a perfectly round, symmetrical layout around the central FRP.

• Gel Filling Compound (Loose Tube Filling Compound and Cable Filling Compound)

Material: Waterproof, jelly-like petroleum compound.

Function: Fills the interior space of the loose tubes. It cushions the fibers, allows them to move smoothly as the cable bends, and acts as the primary defense line against water or moisture vapor penetrating to the glass surfaces.

• Cable Core Binding & Water-Blocking Elements

Material: Water-blocking yarn or tape, held together by a polyester binding thread.

Function: The tubes and fillers are SZ-stranded (twisted alternatingly clockwise and counterclockwise) around the FRP. The entire bundled core is wrapped in water-swellable materials. If water ever breaches the outer jacket, these elements instantly swell to block axial water migration down the length of the cable.

• Outer Sheath (Jacket)

Material: Medium or High-Density Polyethylene (PE).

Function: The outermost defensive armor layer. Black PE provides highly rugged resistance to solar UV radiation, environmental stress cracking, abrasion, and outdoor weathering.