3M??? Cubitron II Roloc Fibre Discs 786C is built for grinding, weld blending, deburring and other tough metal finishing jobs. 3M Precision Shaped Grain ??a tough, hard, sharp ceramic abrasive ??is resin-bonded to a stiff fiber backing. This disc lasts significantly longer than conventional ceramic grain discs, delivering a lower cost per grind with fewer disc changes.