I had never owned a K&F Concept filter before and was pleasantly surprised when I first used it in my landscape photography. The reverse graded ND filters of the popular brands of photo filters are usually quite expensive and this one in particular is cheaper and achieves results that correspond to those of the most prestigious filter brands and are even better. It is made of glass, which is an advantage over resin filters as it is not easily scratched. I really liked the filter cover, which is made of leather with internal protection. In short, I really liked this filter and I am sure that I will use it very often in my landscape shots.

Great quality product at a great price, note these are all Hard Grads which is exactly what I wanted.

This is straight out of the camera and hasn't been retouched. Quality is good, the stones are sharp the water is soft, all in all not a bad product.

A mild light reducer. Can be easily plugged in together with other medium-strength ND filters. Quality like other manufacturers offer. Good optical glass.

Great quality product at a great price, note these are all Hard Grads which is exactly what I wanted.

These filters work, especially in areas rich with sodium/mercury vapour lights, but don't expect total cancellation or miracles. It does help bring out details and colours in the night sky.
I accidentally lost an accessory, but it continues to work. the K&F team contacted me and insisted on sending a new one to make it right. I just received a new accessory yesterday. At least you know that they have good customer service and are willing to make things right for you.

I've been toying with the idea of ​​buying a graduated filter for a long time, although the prices from Nisi, Haida, etc., around 150 euros, have always put me off.
Then I came across the filters from K&F, because the filters were reasonably priced, I ordered them.
The extremely beautiful and high-quality packaging should also be emphasized. Here you get an imitation leather case that is lined with fine fabric on the inside and has 2 magnetic buttons incorporated. This case is again in a nice padded cardboard box, very valuable and stable so I wasn't really disappointed.

Filter holder:
First of all, it has to be said that you need a filter holder system for the filters, which costs around €25 at K&F. This is well made and serves its purpose. Here comes the filter holder in a padded cardboard box. The scope of delivery includes the filter holder and 8 adapters in the size 49mm - 82mm.

So I'm already looking forward to going out into nature with the filter to test it.
The adapter ring is screwed onto the lens thread and the holder is simply mounted on the ring with a snap mechanism. The mount holds securely and doesn't give me any concerns that it might not hold even with minimal play.
The optical quality of the gradient filter is great! I didn't notice any loss in image quality and there's no distortion or vignetting. Furthermore, I could not detect any color impairments or other color distortions. The filter does what it is supposed to do, it easily darkens an overexposed sky and saves me a lot of work in post-processing.

Conclusion
Since I haven't worked with ND filters before, I don't know what I could complain about here.
Overall, I am very satisfied with the glasses from K&F. You get a high-quality, processed filter with top optical quality and a good scope of delivery (artificial leather case). For the price of around €115, it doesn't need to hide behind the other brands. I will soon buy more glasses from K&F.

Just recommend!! The filter system and the 10 stop ND filter works great.

the quality of these filters seems to be on par with others (more expensive ones). The course is clean and evenly straight. The very well thought-out pockets, with their pull-out tab, offer fingerprint-free handling. Clear purchase recommendation on my part...!!!

the quality and package of this set are satisfied, a small pouch to fit the ND filter glass.
By the test, I see there is a little color casting and darkness of this filter but not an issue in comparison to other filters I've used. I could edit it easily in post process.