Otis brushes are designed with a proprietary Tufcor core wire for enhanced durability and performance. The Tufcor technology ensures the brushes are corrosion-resistant, and the tighter twist adds to their superior bristle retention and extended lifespan. Perfect for cleaning 20 gauge shotguns, these brushes are 2 inches long and fit 8-32 threads. Each set includes one nylon brush for gentle cleaning and one bronze brush for tougher residue, providing a comprehensive solution to maintaining your firearms. With Otis brushes, you can trust that your shotgun will stay in peak condition for every shooting adventure.