to create abrasive slurry for effective sharpening with less pressure than an oilstone requires Combination stone has 3000 grit on one face for maintaining and refining, and 8000 grit on the opposite face for polishing steel cutting edges Cleans up easily with Water as lubricant instead of oil Blue plastic hinged box with no-slip can be used as holder for the stone during sharpening Size: 18 * 6 * 3cm Square grindstone size: 6 * 3 * 3cm Knife sharpener stone is made by two sided professional grit stones which are designed to sharpen and polish . Instruction for Use Soak the stone in Water at least 5-10 minutes before sharpening Insert knife into the angle guide Hold knife at correct angle and stroke the blade acrossside Alternate blade sides each stroke or every 2-3 strokes Turn the stone over and polish the blade side Test the burr with paper, no finger Clean the stone and knife, store it in dry place Color: White + Green Material: White corundum Package Contents: 1 x 2-Sided Knife Sharpening Stone 1 x base holder 1 x Square grindstone Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.