AVOS disc (Allows View Of Surface) for a cooler cut than discs without holes, that also allows the operator to see the surface as it is being worked * Zirconia alumina and ceramic aluminum oxide combine to produce fast, aggressive cutting * Zirconia alumina is self-sharpening and durable, allowing for a faster cut rate than aluminum oxide, ceramic aluminum oxide is a self-sharpening grit that is harder, tougher, and lasts longer than aluminum oxide * Closed coat for a higher-quality finish than an open-coat disc * This disc is used with a molded rubber or foam backing pad (sold separately)