It is better to understand the difference in sharpening stone materials before you are going to make any decision. Among the available options in the market today, Waterstone, oilstone and diamond stone are the most common type of sharpening stone. Each of stones comes with advantages and disadvantages. Waterstone and oilstone are available in natural and synthetic models. Synthetic are the most common and easy to find as man makes them. As the use of natural stones (e.g. original Arkansas or Japanese natural whetstones) is has diminished in popularity, they are beginning to rare in the market. Artificial stones have a more consistent particle size and controlled with a tight mechanism in providing high-quality sharpening stone.
It looks like it can be a Sci-Fi film prop. This is a 2 stage type of sharpening system. You'll get a non slip cushion with it which is at the bottom offering stability for the user. It's ergonomic handle provides a comfortable and easy grip. This cushion offers the stability needed when sharpening and polishing your pocket knife to it's absolute razor sharpness. The sharpener does the work as you hold down the grip and simply place your pocket knife to get sharpened by the motions of the ceramic and diamond sharpener wheels. Simply run your dull knives through the device and you'll get the results you've been looking for. This one will definitely help you when you learn how to sharpen a pocket knife on the Priority Chef.