Shur-Line 55538N Beavertail-Poly Premium Select Brush, 4-Inch 100% chemically tapered Polyester for the finest finish & faster coverage Polyester for improved resiliency & Durability Ordinary pet Polyester & nylon filaments lose some resiliency in humid conditions 4-Inch wall beavertail Better coverage, easy clean up and up to 30-percent faster projects speed 100-Percent chemically tapered filament-for precision accuracy High quality pbt polyester filament-for ultimate durability and performance with all paint types Stainless steel ferrule-rust resistant