Each 2 pack contains one bronze and one nylon bore brush. These caliber-specific brushes are color-coded and have the size indicated on the stem, ensuring you grab the right brush every time. Otis brushes have a proprietary Tufcor core wire that is corrosive-resistant and has a tighter twist for better bristle retention and brush life - plus twice the fill of other brushes with bristles right to the end. With Otis brushes you get superior quality and precision cleaning. Rifle/Pistol Bore Brushes available in .22-.50 cal., Shotgun Bore Brushes available in .410-12 gauge.