By adding the special phosphorus-based compound, the long-lasting flame retardant filament Fita is difficult to be ignited and will slightly shrink and massed into conglobation without releasing any toxic halogen gas while encountering flames. Fita has passed the standards in Japan, America, and CNS in Taiwan. The flame retardant characteristics of Fita are long-lasting sealed into the polymer chain, so the function will not be influenced by ageing or washing.