The Bore Tech Proof-Positive AR15 Nylon chamber brushes are made of barrel safe, non-brass material that eliminates the irritating false indication of copper fouling that is found with traditional brushes (with brass) when using copper removing cleaners. This gives you a much more reliable result.
Also, the Proof-Positive AR15 Nylon chamber brushes have twice the amount of extra ridged nylon bristles resulting in double the scrubbing and faster cleaning.
