Anyone who enjoys photography knows what to use an ND filter for. Since my focus is on landscape photography, I can't avoid working with such filters. I ordered this from K&F for my full frame camera. I just got tired of stuffing my backpack with ND filters of different strengths. That's where the Nano-X Pro came in. In order to use it on several lenses I ordered it in the size 77 mm. I then work with step rings to be able to use it on smaller lenses. To say it straight away: the optical quality and the quality of the pictures flashed me! The processing is excellent and very successful. The lens thread is cut very cleanly. The filter can be adjusted from ND 2 to ND 32. The larger levels (apertures) are marked on the ring and are easy to read. It can also only be rotated in this range from 1-5. It doesn't go below or above. So you always know what you have set at the stop. The 77mm. Ring brings 93 gr. on my kitchen scale. Everything is solid and feels very good. The adjustment goes well with slight resistance. It should be so. The optical quality is absolutely flawless and the filter delivers top quality even in difficult lighting conditions. I could not determine any chromatic aberrations or color gradients into green, magenta or anywhere else during pixel peeping. The quality of the filter is unsurpassed, even with backlit foliage or fir trees and reflections from dew. Finally an ND filter that does justice to my limited lenses and full frame sensor. The frame thickness with thread is only 9 mm. Without thread 0.63 mm. So you can also use the filter on wide-angle lenses without edge shadowing. Thanks to the two screwed brass handles and the ribbing of the ring, the filter can be adjusted very sensitively. Conclusion: K&F Concept has delivered a top filter here. What's the point if you put thousands in lenses and then bad filters make the job difficult or give lousy results? Clear 5 stars+ from me. I hope this is helpful in your purchase decision. The price is also relative because you save at least 4 ND filters.