3M's FLEX DIAMOND offers the cutting power of diamond and the strength of a metal bond. They have great durability and long life. Ideal for grinding stone ceramic, composites, glass marble fiberglass and hard to grind metals. Removes material quickly and leaves a uniform finish cutting sanding time in half. For longer life, use water or a bur lubricant as a coolant. 3M Flex Diamond Abrasives are excellent for inside ring clean up, shaping and carving stones. They can be used on metals or stones.