Cubitron 3M 33439 II 3/8" x 13" File Belt - 10 Belts/Box 3M precision shaped ceramic grain continuously fractures into sharp points that cut exceptionally fast, helping increase productivity Precision shaped ceramic grain is engineered to run cooler, reducing metal discoloration/oxidation and the chance of heat related stress cracks Coated with a dry grinding aid to further enhance the product's ability to run cooler and cut faster