Knurling tools are wheeled cutting tools used with lathes to create textured surfaces on workpieces. They're commonly used to add a gripping surface on parts or form serrations on components that lock or fit together. Knurling holders have a cutting head with one or more toothed wheels. Knurling wheels and wheel sets are used to replace worn wheels or change to a different cutting pattern on compatible knurling holders that have replaceable wheels.