Tested to fine finish drill bits and solid carbide tools for aluminum machining. Result is very good. Very fine one - grid 3000 - may be too fine for such job. All in all there is no visible wear of the sharpening surface and material removal is acceptable. Surface is quite flat what is more then enough for knife sharpening. Metallic sharpening plate is glued to a plastic holder with soft silicon glue, therefore it slightly bends if pressed a lot. Strongly recommended.
Great seller!! Highly recommended. The items superb and good.