The Smiths Dual-Grit Synthetic Sharpening Stones are made from a synthetic abrasive material and are used the same as a diamond or a natural bench stone. The 100-grit side is used for aggressive removal of metal and can be used to sharpen a dull or damaged blade quickly. The 240-grit side is for less-aggressive removal of metal and used for sharpening somewhat dull blades that need a quick touch-up or smoothing after sharpening on the coarse side. Excellent for use on pocket knives, sport knives, tactical knives or other cutting tools. Aluminum-oxide stone material. 8L x 2W x 0.75H. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Sharpeners.