The American Mutt series is a unique extra-coarse hybrid ceramic made of a blend of aluminum oxide, silicon carbide, and a small amount of diamond in mixed grits. These stones hog off steel so rapidly that you'll quickly develop a thick "mud" of metal swarf on the stone! However, the inclusion of mixed finer grits causes it to leave a finer finish than one would expect for so aggressive a stone. Perfect for reprofiling, bevel-setting, and repairing damaged edges, especially in locations where power sources for grinders or other electric stock removal are unavailable. Will not blunt like a file if used on dirty surfaces. Economical and high-performance, these stones are sure to please! For best results, fully saturate in water before use and use with heavy pressure. Note that due to the recycled nature of the stone, stone color and performance qualities will vary somewhat from batch to batch.