This coarse pocket-sized diamond sharpening card encourages keeping every edge tuned to its utmost. Using only water for a lubricant, knives can be drawn across the stone at a 20 degree angle, while router and other bits get their flat sides sharpened. The monocrystalline diamond structure of this DMT card is exceptionally strong and doesn"t break away under use. One of the medium or fine cards in a shirt or apron pocket can take a lot of the tedium out of caring for edged tools. Cards are 2" x 3-1/4".