This is a very aggressive 100 grit ceramic flattening stone with grooves. Great for flattening hard ceramic stones, as well as softer 'muddy' stones. Fine stones (3000 grit plus) should be smoothed over with a nagura after using this stone. The deep grooves made by the coarse 100 grit in the flattener will reduce the efficiency of the finer grit stones if they are not smoothed away.
