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, Package of 50, choose: 150 grit, 220 grit, 320 grit.