K&F Concept is synonymous with quality. I already had other filters of theirs, albeit quite old and with several years of service behind them. By virtue of my imminent photographic journey, I decided to opt for something new, always relying on them. I'll show you in detail what are, in my opinion, the pros and cons of their new product. First of all, the packaging is really excellent: the box is made of very sturdy cardboard, even impossible to fold, and then the magnetic opening is very pleasant. The filter is stored in a leatherette case with magnetic closure and not in plastic, which gives the product a finish that we can define as "premium". Inside, wrapped in a protective bag, is the filter. It is a fairly heavy piece, already to the touch it gives an excellent impression. The body is in aluminum, the glasses are of excellent finish. Very thin (and this is good because in this way any loss of sharpness is reduced), waterproof and scratch resistant. Very pleasant (and very useful!) the orange little thing that is used to vary the intensity of the filter itself: the only drawback is not having a limited stroke during rotation, but it is not a big problem, since the ND2 and ND400 are indicated right on the end of the filter itself. In any case, the filter has been constructed in such a way that, even when going beyond the limits, the annoying "X" shadow does not appear. For the moment I've only been able to try it in the city on a rather gloomy day, in the next few days I hope to integrate my review with other shots in the mountains. Who is the filter for? Definitely for those who love landscape photography or for those who have the desire to take long exposures in the city (remaining within the limits of 9 stops): of course, the product is not the cheapest on the market, but just try it for a while to understand which is worth every penny. I'm not a photography professional, but for my use it's just fine.