3M Softback Sanding Sponge, 02604, 4 1/2 in x 5 1/2 in (115mm x 140mm), Fine, 20 sponges per packFlexible foam backing adapts to unique contours and access hard to reach areas Aluminum oxide abrasive offers a long life and fast cut Waterproof bonding system allows for either wet or dry sanding applications Sponges are made for hand sanding Versatile sanding sponges work on many surface materials