4-1/2 in with 5/8-11 arbor. For right angle grinders. Cuts fast and outlasts sanding discs. 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. Wheel size: 4-1/2 in, arbor 5/8-11, maximum rpm: 13,300, tool type: right angle grinder.