3M Sandpaper， Aluminum Oxide， 9000NA-20-CC， 9 in x 11 in Very Fine. 3M sandpaper comes in a variety of minerals and a wide grit range. This very fine-grit aluminum oxide sandpaper is a general purpose abrasive that can be used on painted surfaces， bare wood， and metal. The 9 in x 11 in sheets can be cut to size to use by hand， on a sanding block， or a power tool sander. Sanding is an integral step in preparing a surface to receive a coating. For the best sanding results， sand with the grain of the wood and work through a sequence of grits， from coarse to very fine.