The HORL 3 Kagami whetstone disc has an ultra-fine grit. It compares to the world's finest Japanese whetstones. It provides a mirror finish that's 3x sharper than the results of the HORL Premium Sharpening Set, and must be used after it.‬ To use the HORL Kagami Disc, roll the stone dry along your knife blade for 5 minutes on each side. Then, lightly dampen the stone with a few drops of water and use it for 1 minute on‬ each side of the blade to finish.‬ Not compatible with HORL 2 sharpeners or accessories.