When corn cob and nut shells wont reach every part of the case, Lymans Stainless Steel Media is made to the correct dimensions for getting into hard-to-reach areas inside cases cycling in your rotary case tumbler. Media resists corrosion even when stored away. Size: 5 lbs. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Tumbler Media/Polish.