don't normally use UV filters because they have no function; they only serve to protect the lens glass from scratches and dirt. However, it makes little to no sense to screw a cheap UV filter onto a cheap lens because cheap filters in particular often worsen the image quality, not improve it at all. Exception: I protect a high-quality lens (in my case, one for €1,500) with a UV filter, but of course the filter should also be high-quality. And, I can say right away: This UV filter from K&F Concept in the Nano-X Pro series is absolutely recommended for this purpose because it really is high-quality. The packaging alone gives you an idea of this: The filter is housed in a stylish black box in a pretty case with a magnetic snap closure. The filter itself also makes a very high-quality impression. It is very thin and can be screwed on and off very smoothly. I could not detect any impairment of the image quality in several comparison photos. Therefore, contrary to my usual habit, this useful UV filter will now remain permanently in place on my premium lens as protection against dust and scratches. Even though the price seems quite high, the investment can be worthwhile for high-priced lenses. I give this filter a well-deserved 5 stars.