Tapered bristles are made of PBT (polybutylene terephthalate) filaments chemically treated to produce the unique tapered ends ... it’s more economical,generally PBT filament is used for processing toothbrush, food-industry brushes, paint brush and cosmetic ... in 2012. We are a professional manufacturer of filaments for toothbrushes, tapered filaments, abrasive filaments, and industrial filaments. ...