Outers .338 - .375 Caliber Rifle Bronze Bore Brush (8-32 Threads) Made of the highest quality materials Hunting gun Cleaning supplies Another quality Bushnell product Precise brush diameters to assure complete bore coverage on specific calibers Brushes feature bristles that are chemical resistant for durability Specially-engineered looped core and tip to protect muzzle, chamber and rifling Phosphor bronze bristles No polymer residue