OUR PREMIUM BLACK SILICON CARBIDE SANDING BELTS OFFER A GREAT FINISH. CONSTRUCTED ON A VERY STURDY "Y" WEIGHT BACKING PROVIDES GREAT BACKBONE ON THIS BELT TO HANDLE TOUGH FINISHING. SELF SHARPENING BLACK SILICON CARBIDE IS GOING TO GIVE YOU A GREAT FINISH WITH LONGER BELT LIFE THAN STANDARD AO BELTS.