HFFR PP filler (Halogen-Free Flame Retardant Polypropylene filler) is a type of filler rope used in cables to improve their flame retardant properties. It is made of halogen-free and flame retardant polypropylene material, which does not emit toxic gases when exposed to high temperatures. HFFR PP filler is also resistant to high temperatures and can withstand temperatures of up to 90°C. It is commonly used in low-voltage and medium-voltage power cables, communication cables, and optical fiber cables. The semi-conductive version of the HFFR PP filler rope is also available, which provides additional shielding against electromagnetic interference.