Wheel diameter: 4 1/2 inGrit/Grade: A24R/Very coarseMaterial: AluminaEachWheel diameter: 4 1/2 inGrit/Grade: A24R/Very coarseMaterial: AluminaDeWalt® AO Type 27 General Purpose Depressed Center Grinding Wheel, A24R, 4 1/2 in (Dia), 5/8-11http://s7d5.scene7.com/is/image/Staples/s0482698_sc7?$std$http://s7d5.scene7.com/is/image/Staples/s0482698_sc7?$thb$http://s7d5.scene7.com/is/image/Staples/s0482698/DeWalt-AO-Type-27-General-Purpose-Depressed-Center-Grinding-Wheel-A24R-4/product_854779DeWalt® AO Type 27 General Purpose Depressed Center Grinding Wheel, A24R, 4 1/2 in (Dia), 5/8-110.00