The typical "super-abrasive" most commonly used in the automotive industry is diamond. Diamond abrasives create very low-wearing tools. Diamond tools stay straight and are the only tools to cut some of the cylinders with specialty coatings or materials, such as Nikasil. Sunnen recommends the use of a dedicated DH-Series Tooling for the diamond abrasive machining. Even though diamond tools can be mounted in conventional CV tooling, the DH cutting heads have the correct geometry and carry the appropriate number of stones to produce the required roundness.