3M (815) 02604 3M™ Softback Sanding Sponge, 02604, 4 1/2 in x 5 1/2 in (11.43 cm x 13.97 cm), Fine-320/400, Colour: Gray, 3M Stock No. 7000000589

Coated with aluminum oxide, 3M™ Softback Sanding Sponges can be used wet or dry when sanding on wood, fiberglass/gel coat, marine paints, metals and plastics. They are flexible and conformable to allow for hand sanding in areas inaccessible to machine sanders. Fine grade ranges from grade 320 to 400 grit.