Metabo® Depressed Center Wheel, General Purpose, series: Original Grinding® Long Life, 4-1/2 in Wheel dia, 1/4 in Wheel Thickness, 7/8 in Center Hole, Arbor Connector, A24R Grit, Coarse Grade, Aluminum Oxide Abrasive, Wheel Type Number: Type 27, 13300 RPM Maximum, Resin Bond, Applicable Materials: Steel and Ferrous Metals, Wheel Hardness: R, Black Wheel, Yes Reinforced. Metabo® 616307000 Original Grinding® Long Life General Purpose Depressed Center Wheel, 4-1/2 in dia x 1/4 in Thick, 7/8 in Center Hole