The AR15 Carbon Boss was designed to provide you with the most comprehensive carbon removal capabilities ever. With a rotating pin punch, cotter pin puller, interior bolt and exterior bolt scrapers, bolt lug scraper, bolt cam pin scraper, small and large firing pin scrapers, embedded 360 degree phosphor bronze bolt tail brush, replaceable rotating multi-surface bolt brush, bolt face scraper, bolt carrier scraper and firing pin face scraper this tool is carbon's worst enemy.