Here are a few elements you need to keep an eye on to make sure you buy the best manual knife sharpener on the market. First, price Buying an excellent manual sharpener won't cost a fortune, but you need to make sure that the product is a really good value for money. Second, blades Whether your chef's knife is Japanese knife or European Style knife, double-beveled or triple beveled, or even outdoor knives, you need to pick up the manual sharpener that works well with it. Third, Material of Abrasives Abrasives are the surfaces that straighten, hone, and polish your knife blade directly. The most popular in descending order are Diamond abrasive Sapphire abrasive Ceramic abrasive tungsten carbide abrasive synthetics abrasive Fourth, stages and slots Most electric knife sharpeners and manual knife sharpeners have one sharpening stage, but if you are looking for more specialty and want to hone your knives first then sharpen them, you can buy a 3 stage or 4 stage knife sharpener. Fifth, safety Whether it is an electric knife sharpener or a manual knife sharpener, pick up the tool that has a nonslip rubber base and rubber handle.