When you use the Aligner sharpening kit by DMT, you are sure to use a constant angle while sharpening. That is ideal to get your knives back to razor sharpness. The Extra Extra Coarse-stone provides you with a tool for the more aggressive metal removal, as well as a safe alternative to sharpening on a machine. Always take into account that a diamond sharpening stone has to be made ready for sharpening. Only after 5 to 10 knives the stone works as intended.