Webb Abrasives 366012 Z-Foam Block Sanding Sponges, Medium/Coarse Grit, 2 5/8" x 3 7/8" x 1" (24-Pack) Dimensions: 2 5/8" x 3 7/8" x 1" 4-Sided med/coarse grit coating: brown aluminum oxide Use wet or dry; features clog resistant technology (crt) Backing material: pu blue foam (polyurethane), solvent-free Foam hardness: firm, for high removal capacity