Vivreal Water Stone Dual Whetstone Knife Sharpener Sharpening Flattening 1000/4000 1. Special proportioned white corundum made waterstone, high hardness and wearproof. Fine texture and sharpening force ensure sharpening speed and quality. 2. Suitable for top grade kitchen cutter, outdoor knife, precision tool. 3. 1000# finely sharpening, small particles whetstone. Dense space and fine texture, repairing small knife in a short time and consolidating blade point. 4. 4000# for refined sharpening.