Silicon carbide is the abrasive of choice for tumbling because it has a Moh's hardness of 8+, incredible longevity, and is quite effective. This 500 & Finer Silicon Carbide Tumbling Grit has a fine grain and is typically used in Step 3 of the tumbling process. The 1 lb. package will process 10 - 14 pounds of rock. This product is graded, with a tight range in grit size. If you're looking for a pre-packaged solution to all your tumbling needs, check out our Rotary Tumbling Kit and Vibratory Tumbling Kit.