3M 2604 Fine Softback Sanding Sponge
An innovation in coated abrasives for hand sanding applications, features aluminum oxide mineral coated on a foam pad with a waterproof bonding system.  Fine grade 320-400. Provides flexibility and conformability to allow for sanding by hand in areas inaccessible to machine sanders. Use wet or dry when sanding on wood, fiberglass/gelcoat, marine paints, metals and plastics.