The Mueller-Kueps Conical Eraser Kit, No. 282 260/KIT, includes six erasers made from high-quality rubber and one adapter for a drill. At 60mm in diameter, the erasers are designed to reduce time spent cleaning rims. Use with an electrical drill or cordless drill. For best performance, the company recommends to use at 500 rpms. If used at proper speed, the eraser will not leave any residue on the rim. The erasers will not damage or scratch aluminum rims.