3M Scotch-Brite non-woven SR-ZA sanding star uses aluminum oxide as the abrasive material and has a diameter of 2 in. Since this product is non-woven, Grade is generally used to describe the abrasiveness; with the 13371 having a coarse grade. The arbor attachment allows for easy mounting to the tool or pad. 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 sanding star can be run at a maximum speed of 24000.