Henckels Twin Sharp Duo knife sharpener is suitable for all knives with a fine edge, with the exception of coated knives. The stainless-steel sharpener comprises two modules, which are marked on the sharpener. The first module features steel wheels for coarse sharpening and presharpening, and the second module uses ceramic wheels for fine sharpening and smoothing. This sharpener works well for both right- and left-handed people, features rubber feet so it won't skid on the countertop, and measures approximately 8 inches across and 3 inches tall, so you can store it in a drawer or display it in a small space. To use, place the knife sharpener on a flat surface, pressing down slightly with one hand. Draw the knife blade with a little pressure towards yourself, repeating up to five times for the dullest blades. For very blunt knives, use the first module and then the second. Knives with a bit of bluntness may require only the first module to bring back the original sharpness. Check the results by cutting into a sheet of paper.