The coarse single-sided sanding sponge 3M Softback Sanding Sponge 03808 is highly adaptable, suitable for hand sanding hard-to-reach areas before applying the final coat of paint. It can be used for dry or wet sanding of paints, metals, plastics, or fiberglass. After use, simply rinse the sponge and you can use it again. Abrasive: aluminum oxide.