4-1/2" x 7/8", 40 Grit, Flap Disc, Extended Performance Flap Design Lasts 2.5 Times Longer Than Standard Flap Discs, Premium Zirconia Cloth Provides Aggressive Grinding Action 40 Percent Faster Than Standard Flap Discs, Proprietary Design Provides Removal Rate Of A Grinding Wheel With Finish Of A Fiber Resin Disc.