EXCELLENT value for money.
To the touch it shows good material, there is nothing plastic, it seems resistant and the turn is soft enough to move it without a problem but it will not move due to a silly blow.
The image quality is very good, it adapts perfectly to the lens and I have not noticed vignetting.
It is true that if it exceeds the maximum, the "x" effect is appreciated, but knowing it, there is no problem.

In short, I would buy The K&F Concept ND Filters again. For that price you can't ask for more.

Admittedly, I was a bit skeptical that an adjustable ND filter could really be good. You usually pay more for an ND filter in one strength.
I don't use a filter that often, but it comes in handy every now and then, for example when I want to take pictures with an open aperture of 1.4 in the sun or for photos by the water.
So I ordered the adjustable ND2-ND400 from K&F Konzept. I already have backpacks and a tripod from this manufacturer and I am very satisfied with them.

*** Delivery ***

As always lightning fast with Amazon, the filter came securely packaged with Deutsche Post.

*** Quality / First Impression ***

The filter is packed in a small plastic box, which can also be used for storage. Here I would like a recess inside so that the filter does not always slide back and forth.

First and foremost I bought the filter for my EF-M 11-22 IS STM lens (55mm filter diameter). I have a step down adapter for my EF-M 32mm 1.4 so that I can also use the filter on the smaller diameter lens.

The filter makes a high-quality impression. Nothing rattles or rattles. It attaches easily and turns buttery smooth. Not too loose and not too tight. There is a scale from MAX to MIN, so you can continuously adjust the filter to the desired strength between ND2 and ND400. However, you should not go beyond the MIN and MAX markings, otherwise there will be a black area in the picture.

The image quality is great, I can't see any loss of quality or loss of sharpness.

*** Conclusion ***

If you don't want to carry around several filters and change them all the time, an adjustable ND filter makes perfect sense. Also and especially if, like me, you don't want to spend so much money on several strengths at once because you don't use the filters all the time.
A landscape photographer who uses filters for almost all photos will certainly get an expensive plug-in system, which makes sense. But for the amateur photographer who would like to photograph a stream with soft water from time to time or with a wide open aperture in strong sunshine, a variable filter makes perfect sense. The price / performance ratio is really excellent with this filter. From me there is a clear purchase recommendation!

One of the best photographic filters ever for quality / price ratio, especially for quality.
It is sold with a comfortable rigid and padded box for storage after use.
K&F is a safety for what concerns filters and additional lenses for objectives.
100% recommended !!!

A filter of this type was missing from my kit. High quality of the lens and I can recover up to 9 stops to use for long exposure photos in the daytime. highly recommended.

I bought the K&F Concept ND filter for my Sony Alpha 7 III. I use the 67mm version.
The filter arrived the third day. Everything was well packed and undamaged.

The processing is really impressive. Very clean glass and no scratches or anything like that.
The intensity of the ND filter can be continuously adjusted from ND2 to ND400.
I took a few test photos with the filter and am absolutely satisfied.
The only drawback for which there is a star deduction: At the maximum filter level you have a bluish shimmering X in the photo. This is a bit annoying, but if you turn the intensity down to just below the MAX level, it disappears again.

All in all, you can't go wrong with the ND filter from K&F Concept. At a reasonable price you get a universal ND filter. I give it a clear buy recommendation and because of one shortcoming 4 stars.
I hope I could help :-)

I ordered the ND filter from K&F Concept because I already have one in a different size and am very happy with it. With variable filters, there is a risk that these vignettes will conjure up images. That is not the case here. However, the filter could not be screwed onto the thread correctly. After a short contact with the seller's customer support and description with photos, a new product was sent to me. I can't complain about that.

Excellent purchase, I already had an ND filter but not with variable thread. The attached photo I entered a competition with the title "... it's night ...".

I've been looking for an ND filter that is cheap but also of high quality for a long time, I found it here. The K&F Concept ND filter is of high quality and comes with a case, the adjustment ring turns comfortably and does not slip immediately. I have used the filter twice so far and will continue to use it and can only recommend it.

Very useful product and of crazy quality, it is not fragile at all. I took 2 photos with 5.6 aperture and 1.6 "without filter it was practically white with exposure +5, with exposure reached 0.0

K&F Concept Adjustable ND filter with a very good price-performance ratio in top quality
You have to try a bit, since there is no scale, but with a little practice you can take great pictures.
(Picture was taken with a 2sec exposure at max ND filter value)