Otis Bore Brush Pack 17HMR/.177 WSM/.177 Cal Airgun brushes are 1" in length, allowing for limited breech cleaning. Otis brushes have a proprietary Tufcor core wire that is corrosive-resistant with a tighter twist for better bristle retention and brush life. With twice the fill of other brushes and bristles right to the end. Two per package- one bronze and one nylon.