The product is one of those pull-through sharpening contraptions that are popular with e.g. butchers or hunters and the like. It’s absolutely resonable priced and has a high quality look and feel to it. The two spring loaded swivel arms are mounted on a solid alumium frame and, where they make contact with the blade, are coated with tungsten carbide, a very hard and durable material. There are two ways of using it:
For an initial rough grind, hold the frame with one hand and watch your fingers! Gently pull the knife through the opening with only little downward pressure (don’t use too much force). Do only three to four strokes – with the handle being higher than the tip of the blade.
For the following fine sanding, do the same thing again, but with the handle being lower than the tip (see image #2). Done.
They say you can sharpen all kinds of knives with it (with the exception of ceramic knives), including serrated and one-sided blades, but I only tried it with ordinary kitchen knives, my pocket knife and my fishing knife. The results after only a few strokes are repeatably very good and entirely acceptable. Also, I didn’t discover any damages to any of the blades tested (which is said to occur on cheap sharpener models). In summary, this gadget can not replace a thorough whetstone finishing but for the occasional kitchen use it provides an overall very solid bang for the buck. Recommendation!