For jobs that require extra strength, the newest and toughest of the Ultra/Pro line is Extra/Firm. NylonPlus filament, exclusive to Wooster, allows for superior stiffness and cut-in control. It's able to maintain a sharp edge even in hot, humid conditions. Made from 100% nylon, Ultra/Pro Extra-Firm is very durable, and cleans much more easily than brushes that use polyester to achieve extra stiffness. It's the perfect choice for all thick paints or primers and exterior use, as well as for edging walls and painting trim or woodwork. Ultra/Pro Extra-Firm has both excellent pickup and release to provide the fastest results. For the strong touch, look for the purple and black filament and the teal stamp on the handle. The Wooster Brush Company has been manufacturing innovative, high-performance painting tools right out of Wooster, Ohio USA since 1851. You can feel confident knowing Wooster is the name behind your painting tools.