DEWALT DWA8203 80 Grit Zirconia T29 Flap Disc, 4-Inch X 5/8-Inch Zirconia grit enables 3X faster material removal than fiber resin metal sanding discs Premium abrasive cloth provides up to 15 X longer life than fiber resin metal sanding discs Type 29 fiberglass backing provides grinding angle of 20-25 degrees