Long-lasting conical zirconia abrasive discs take the place of resin fiber discs and grinding wheels. Help make weld joints almost undetectable and reduces need for final filler. Flap design runs cooler to reduce panel warping and won't gouge metal like ordinary grinding discs. Each flap disc will out last approximately 15 resin fiber discs. Order 1-2 grits coarser than resin fiber discs. Use on your high-speed grinders with 7/8 in arbor. Max 13,280 RPM.