Kotai Sharpening Set - 180/800 Grit Restore your blades to their original sharpness with this double-sided whetstone. The Kotai 180/800 grit sharpening set includes: 1 x 180/800 grit double-sided ceramic whetstone. 1 x Anti-slip natural bamboo base for safety and comfort. 1 x 15° angle guide for easy and precise sharpening. 1 x Corundum stone flattener to extend the lifespan of your whetstone. 1 x How-to sharpening manual. Even the best blades will lose their initial sharpness over time. Whetstones, also known as water stones or sharpening stones, are used to grind and hone a knife’s edge. The KOTAI 180/800 ceramic whetstone offers you two grits: a coarse 180-grit side to grind away rougher edges, and a fine 800-grit side to put the final touch for a razor-sharp edge. Extra large (200 x 80 x 30 mm) for more even and easier sharpening. Double-sided so you can sharpen your knife from beginning to end with a single stone.