Ceramic aluminum oxide is a self-sharpening grit that is harder, tougher, and lasts longer than aluminum oxide * Type 27 flat shape, has less surface area than type 29, and its flat design helps obtain a smoother finish * Full Y-weight polyester, resin bonding system with heavy-duty fiber backing for increased strength, durability and tear resistance * Durable fiberglass backing plate helps absorb vibration with no smearing * "Supersize" grinding aid provides a cooler cutting and faster cut rate