Master Mechanic, 4″ x 5/8″, 80 Grit, Zirconia Flap Disc, Enables 3 Times Faster Material Removal Than Fiber Resin Metal Sanding Discs, Premium Abrasive Cloth Provides Up To 15 Times Longer Life Than Fiber Resin Metal Sanding Discs, Type 29 Fiberglass Backing Provides Optimal Grinding Angle Of 10-25 ree., Allows Full Use Of Disc & Won’t Mar Work Piece, Applications Include Weld Blending, Removing Weld Slag, Deburring, Surface Finishing & Preparation, Edge Blending & Camfering, Max RPM Rating 15,200.