The Blade Tech Whetstone 180 (extra coarse) & 600 (fine) Grit is an excellent quality stone offering two different sharpening surfaces. The 180 grit is best suited to reshaping particularly dull blades. The 600 grit surface is used to apply a final cutting edge to the blade. The stones are best used by submerging them in a bath of water for 5 minutes prior to sharpening. This offers the sharpening surface the best possible lubrication during sharpening. All of the Blade Tech Whetstones are supplied with a rubberised non slip base for secure and easy sharpening. Sharpening surface 18 x 6 cm.