3M Cubitron II File Belt 3/8X13IN 60X 10BOX features 3M's tough and best in class Cubitron II mineral. Grains of ceramic/aluminum oxide blend are precisely-shaped, uniformly-sized and vertically oriented. Slices through hard metal for fast cut. Cubitron II abrasives run cooler, reducing risk of metal discoloration/oxidation and heat related stress cracks.