3M™ Cubitron™ II Hookit™ Clean Sanding Abrasive Disc 31481 (6", 220+ Grit, 50/Box). 3M Cubitron II Clean Sanding Hookit Disc 31481. 3M Cubitron II 31481 Clean Sanding Discs feature 220+ grit precision-shaped ceramic abrasive technology for fast cutting, long life, and superior dust extraction.