3M CUBITRON II HOOKIT GRIT FAIRING BOARD FILE SHEET Features 3M Precision-Shaped Grain, triangular-shaped grains that cut at least 30% faster and last at least 30% longer than other conventional ceramic abrasives. 3M Hookit hook-and-loop style abrasive attaches firmly, removes quickly for fast change-out. Precision-Shaped Grain (PSG) technology employs microreplication to obtain sharp and uniformly sized triangular grain. Triangular PSG abrasive grains are sharp and cut exceptionally fast.