I have extensively tested this "K&F Concept Nano-X PRO series polarizing filter" with my two 67mm Sony lenses (85mm + 24mm focal length) and would like to share my experiences today:

The packaging of the filter is impressive, because "K&F" has packaged this "Pro" filter in a very attractive and high-quality way. The scope of delivery includes a bag with parts made of leather, which is softly lined on the inside and is used to store the filter. In addition, there is an extra packed cleaning cloth. The bag has a magnetic closure and is very well made all around. The filter itself is also very well made, it has a brass frame and can be easily screwed onto my two lenses. Turning the filter to adjust it also works well. Due to its slim design, the filter does not apply too much to the lens.

The surface of the polarizing filter has a 36-layer nano-coating on both sides, making it waterproof, dirt-resistant and scratch-resistant. The coating makes the filter robust and I assume that this means that it is durable and that I can shoot with it for a long time. I am also completely satisfied with the properties of the filter, it reduces reflections (e.g. in water) by eliminating polarization by around 99% and the contrast of the image (which is easy to see in photos of sky/clouds) is increased.

I have already photographed the landscape with the filter and I am very satisfied with the image quality. I have not noticed any visual impairments from using the filter. I can for the "K&F Concept Nano-X PRO series polarizing filter"