DEWALT DW8310 4-1/2" x 7/8" 120 Grit Zirconia Angle Grinder Flap Disc 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