Lyman Turbo Case Cleaning Media is a great choice for cleaning tarnished cases. A few hours in a tumbler and cases are clean polished and ready to load. Made from natural processed corncobs, corncob media is tough enough to clean brass that has minor tarnishing yet soft enough to not damage the casing. Media is reusable for multiple tumbling cycles. Proper brass cleaning extends the life of cases and reloading dies.