AmazonFor knives that require sharpening, this tool has three slots: coarse, medium, or fine. Start with the coarse slot if your blade is very dull and then move on to the medium or fine slots.Start by holding a knife in your dominant hands. Grab the handle of your sharpener with one hand and place it on a flat surface using the other. The heel of the knife should be inserted into the coarse slot. Pull the knife towards you by pulling the knife through the slot. If you have to, repeat the process three to five more times.Promising review: This is a useful little tool for anyone who doesn't know how to sharpen knives. It is a handy tool that I use whenever I need my knife to be sharpened. Simply insert the blade in the sharpener, and then pull it towards you. You don't have to worry about it getting in the wrong sharpener. All of them work! Amazon CustomerIt's only $9.99 on Amazon from BuzzFeed’s Goodful Collection.