The EdgeLogix Whetstone 6" Two-Sided Knife Sharpener 400/1000 Grit (15050) is a double-sided silicon carbide 400/1000 grit stone. It's an ideal size for mid-size kitchen and sporting knives. The 400 grit will re-sharpen dull and damaged knife edges while the 1000 grit will refine the edge to shaving sharpness. It works best when used with water.