They meet or exceed military specifications and are designed to satisfy the shooter who wants the best tools to maintain his or her guns. The core is a single piece of brass wire that passes through the threaded brass coupler, guaranteeing that the core will never separate from the coupler in the barrel. Each brush contains the maximum number of bristles that can be inserted for the caliber. 20% more than standard brushes. Because of their density we recommend that Tipton Best Bore Brushes only be used with quality a one-piece rod and an appropriate bore guide.