3M Scotch-Brite non-woven 9145S sanding disc set. Comes with the following: 4 1/2 in Blue Very Fine Disc, 4 1/2 in Brown Coarse Disc, 4 1/2 in Gray Super Fine Disc, 4 1/2 in Maroon Medium Disc, 9145 Disc Pad Holder. 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 disc set can be run at a maximum speed of 13000 RPMs.