Flap Disc, Blue Zirconia, 36 Grit Type 29, Depressed Center, 4-1/2" with 5/8-11 Arbor ZA36, for right angle grinders. Cuts fast and outlast sanding discs 10-to-1. Great flexibility. Ideal for rough or fine finishing. Multiple layers of zirconia cloth flaps constantly exposing new extra sharp grinding points. Laminated by state-of-the-art automated equipment. Reinforced fiberglass backing plate. Each disc balance tested for vibration-free grinding/finishing. Max RPM: 13,300