3M SandBlaster 9679 Multi-Layer Grinding Disc, 60-Grit, Medium Grade, Cubitron Mineral, 4-1/2 in Dia

They are made with a durable Cubitron cents ceramic mineral, resulting in less burning and a longer disc life. In addition, as the multi-layer disc is used, fresh abrasive is exposed as the product wears, enabling simultaneous material removal and finishing in one step.