3M Cubitron II Type-Q quick change depressed center wheel uses ceramic aluminum oxide as the abrasive material and has a diameter of 4 1/2 in. In addition to the other aspects of these parts, another important component of these is the thickness. This 3M part is 1/4 in thick. All abrasive products that rotate or spin, such as the ones in this category, have a maximum speed at which you can run them. This 3M quick change depressed center wheel can be run at a maximum speed of 13,300 RPMs