Use our 400 grit sharpening stones for achieving a fine edge on your blade. Unmounted aluminum oxide sharpener stones must be mounted to a "stone blank" (sold separately) to be utilized with the Edge Pro sharpening systems. Customers who go through many knife sharpener stones can remove their worn out stones from the existing stone blank and mount their unmounted stones themselves saving 50% off the mounted stone price. We suggest mounting the stones using 3M's Super 77 adhesive spray.