K&F is known for having photography products within everyone's reach, both in its Professional and Amateur ranges. In this case we have a filter with two functions, Polarizer and Neutral Density, the latter variable in 5 positions. It is delivered in a sealed box and inside it is the synthetic leather case that contains the filter inside a plastic bag. The first detail that draws attention is that to remove the filter from the case, it has a strap that when pulled makes the filter come outwards, making it easier to grab, especially if we are wearing gloves due to the cold. The manufacture of this one is made of very high quality aluminum and with a magnificent finish, far superior to others that I have from a German brand well known by all professionals in the field. It has 5 ND filter positions ranging from 1 stop (ND2) to 5 stops (ND32), but you have to look at the filter to know what position you leave it or want it in, they do not have a partial locking system, that is, there is no click that tells you the exact position and that also serves as a lock. I say this because then if you want to adjust the polarizer, it is very likely, or rather you have an 80% chance, that the ND position has moved and this forces you to look again and see if it is at the point you need or want, since otherwise areas with more ND than others will appear, what some call the X effect or something similar. As for image quality, it is very good, the photo you take will not lose quality or sharpness when using this filter, just as you will not notice any color vacation. Perhaps the ND 32 raises the colour temperature by 200-300ºK, but it is so ridiculous that it is imperceptible. As for vignetting, it is three quarters of the same, except for the jolt produced by the optics itself. I have hardly noticed this effect when using the filter, just a little darkening at the edges in the ND32, but I insist as with colour, it is ridiculous, practically imperceptible. As for the polarizer, there are times when it is difficult to get the exact point, the polarization travel is very small compared to others that I have with a smaller diameter, but it is a matter of getting used to it and with the passage of time it stops being a "problem" This type of filter is aimed at all photographers, but especially at people who like to do landscape photography, although with limitations if we compare them with fixed or mount filters (also more expensive) and it can be a very valid alternative because the angular lenses that we use have very open F / Nº and yes or yes, you have to use it if you want to have optimal or specific results, such as the silk effect of water or clouds, while removing reflections and enhancing contrast and color thanks to polarization, if you want to use it, but since it is there, my advice is to use it. I hope this review has been useful to you