3M Greencorps Roloc roll-on sanding discs are a heavier duty sanding disc than standard 3M rolocs. They come in 2" and 3" diameters and multiple different grits depending on the desired result. They work great for rust and paint removal, spot weld cutting, gasket removal and metal shaping. They have aluminum-oxide grit for optimal resistance to wear and are easily changed by unscrewing and screwing in a new one.