Lasts Longer - Coarse Aluminum Oxide Mineral Last 2.5X Longer Than Conventional 3M Sandpaper. Smooth Bondo Spot Putty - 220 Grit Is Great For Shaping Glaze And Spot Putty. Super Strong Abrasive - 3M'S Mineralw Make A Tough Abrasive That Self-Fractures To Expose New Edges Which Allows For High Durability.