These cutoff discs are great for quick removal of stubborn objects such as rusty nails and bolts. They also work great when scoring objects. They work great on wood, metal and even ceramic. They are composed of super-compressed abrasive material that has an outer layer of fiber reinforcement for extra strength. The standard 1/8" arbor fits perfectly in most dremels. The discs are so useful that we recommend have plenty on hand for whatever your need may be!