The premium bore brushes feature a distinctive cobalt blue fiber, ensuring they stand out from other types of brushes. Designed with a thicker and stiffer grade of fiber, these brushes support effective back-and-forth cleaning action, surpassing traditional brass and bronze brushes in durability by lasting approximately 8 - 10 times longer. Each brush is meticulously crafted with a tighter winding and a higher fiber density per inch, enhancing its cleaning efficiency. When used in conjunction with IOSSO Bore cleaner and triple action solution, these brushes effectively remove all types of fouling, including copper, lead, plastic wad, and carbon burn, significantly reducing cleaning time and delivering an exceptionally clean bore. The blue brushes are a registered trademark of IOSSO products.