Aluminum oxide is durable and the most common abrasive grain * Open web construction resists clogging * Abrasive held within a flexible nylon web, laminated to a PowerLock nylon backing, permits high grinding speeds * PowerLock Type I discs have a snap-on central hub and mount to Norton TP or 3M Roloc TP back-up pads * Used with a molded rubber backing pad (sold separately)