The EdgeLogix Safety Grip 2 Stage Ceramic Sharpener offers two stages of sharpening that work on all straight-edged knives. The ultra-strong suction cup secures the sharpener safely to the countertop, preventing slipping and shifting. Use Stage 1 (400 grit coarse ceramic wheels) to sharpen a dull knife. Use Stage 2 (1000 grit fine ceramic wheels) directly after stage 1 to hone the knife. Regular maintenance of your already sharp knives can be done using Stage 2.