The magnetic stainless steel tumbling pins are designed to clean brass cases giving a like new look. Unlike other media like corn cob or walnut, stainless steel doesn't create dust and also cleans the inside of cases, primer pockets, and flash holes. Stainless steel also doesn't damage brass and lasts for multiple uses. Perfect amount to use with the rotary tumbler lite 304 magnetic stainless steel 1 mm x 7 mm pin size Pins scrub inside the case body as well as inside the primer pockets Tumbling with SS pins will clean your cases inside and outside