A dull knife will never produce the best results. Keep your knives razor sharp with this combination grit starter sharpening stone from Mercer. Made from corundum, this sharpening stone is dual grit. With a coarse 400 side and a fine 1000 side, this stone repairs damaged knife edges and sharpens dull or blunt edges back to razor sharpness and optimum performance level. Its non slip silicone base prevents damage to workspaces and provides stability while sharpening. Promising customer satisfaction, this stone comes with a manufacturer's lifetime warranty against defects.