New Dremel #415 Dressing Stone A solid block of extremely hard abrasive measures approx. 1"x3/8". Ideal for cleaning and reshaping grinding stones for specific applications. - For best results, insert the accessory bit all the way into the tool and then back it out slightly before tightening down. This provides plenty of shank for the collet or chuck to hold onto.- Abrasive accessories will wear out and change shape during use. Its a good idea to balance abrasive points and grinding stones before each use.- To rebalance a worn accessory, place the dressing stone in a vise to hold it in place. After making sure the accessory is mounted securely in the tool, turn on the tool and file the point or grinding stone against the dressing stone to the desired shape.