Scotch-Brite Light Grinding and Blending Discs use ceramic aluminum oxide, a blended ceramic mineral engineered to fracture frequently and surpass aluminum oxide abrasives in both cut-rate and durability. Available in both Heavy Duty (HD) and Super Duty (SD) coarse — depending on your finish and aggressiveness needs — this proprietary ceramic blend is built to cut fast and handle intense stress applications. Thanks to these performance benefits, Super Duty (SD) discs are able to grind and blend in a single step where a 3 mil or greater paint thickness is being applied, while Heavy Duty (HD) discs are made for applications with less than 3 mil — making Scotch-Brite Light Grinding and Blending Discs a high-performance, 'all-in-one' solution.