Mercer Industries 332024 Zirconia Flap Disc, High Density, Type 29, 4-1/2" x 7/8" Grit 24, 10 Pack Type 29 High Density Flap Discs for 4-1/2-Inch x 7/8-Inch Angle Grinders, Max RPM 13,300 High quality Zirconia grain features a resin on resin bond Cool cutting and resistant to heat and moisture Does the job of a grinding wheel and a fiber disc Strong poly/cotton backing to extend the life of the disc