Tapered PET paintbrush filaments are made from polyethylene terephthalate (PET) with a standard density of 1.34 g/cm³. They offer excellent paint absorption, smooth application, durability, and flexibility. Common diameters range from 0.10mm to 0.60mm, with taper ratios of 1:5 to 1:15 for fine tips. Modified PET filaments may have densities up to 1.38 g/cm³, enhancing performance for professional painting.