Varnish and enamel brush. Satin-edge nylox and orel polyester filaments. XL brushes are highlyrecommended for both interior and exterior painting projects with all paints. The stiffness retention of XL brushes makes them especially high-performing for outside painting under hot and humid climate conditions. Each XL brush style has its own unique hand chiseled formulation for maximum paint lift and smooth, no-drag application.