These Magnum discs feature the longest-lasting aluminum oxide abrasive bonded on durable, reinforced plastic that ensures extended life and outlast paper discs. With their brass centers, these flexible discs can be changed instantly. Great for finishing carvings! Use discs with a snap on/off disc mandrel, item 15097. Maximum speed 30,000 rpm. 7/8" Diameter. 25 pieces each in fine (320 grit), medium (220 grit), coarse (150 grit).