Ceramic media, small size, (5/32" x 5/16"), is sold in one pound packages. Ceramic media is non-abrasive and used as a burnishing media for jewelry metals and also used as a filler or separating material when tumbling stones.  The ceramic media speeds the process of tumbling by getting between flats and into small crevices.  A combination of the two sizes of ceramic media is recommended by tumbling experts.