I had been hesitating between several brands for a while to choose a filter holder for ND and GND filters. I took advantage of a flash sale to acquire this kit. I am not disappointed.
the set seems robust and easy to store.
The case, quite pretty, has 5 compartments, 3 of which, for square ND filters, can be lifted by means of a ribbon. On the back of the case, there is a ring to pass a strap and a passage for a belt. I would have liked a slightly more spacious compartment to house the adapter rings with the CPL filter when it is disassembled.
The assembly (or disassembly) of the elements is well explained in a manual in several languages, including French.

Main positives:
No color cast or loss of sharpness on the first tests carried out.
The plastic frame with its tabs to handle the ND filters.
The CPL filter installation system on the filter holder.
the knurled knob for mounting the adapter ring and the rotating block of the filter holder.
The very accessible wheel to control the polarizing filter.
Firm hold of the square filter on the filter holder.
The robustness of the metal filter holder.

If you have to find some negative points:
The slightly too vigorous maintenance of the square filter in the filter holder.
the click too hard to lock the CPL filter in the filter holder.
No pouch to independently protect the CPL filter in the case.
No CPL protective cover when the assembly is installed on the lens.

The filter does what it should, it extends the exposure time. A Vignettietierung or wrong color reproduction I could not determine so far. The packaging of the filters is very good and practical, some higher-priced filters can not do so well.

Very high quality ND1000 K&F Concept square filter set consisting of glass filter, filter holder and lens adapters for the filter holder.

The package is divided into 3 parts:
1. a bag with metal adapter rings for lenses with different diameters.
2. a box with the filter and its leather carrying case.
3. a box with the filter holder.

The adapter rings allow us to put the filter holder on any lens, since we have a large number of different diameters. They are made of black metal and well made. With inscription on each ring of the corresponding diameter.

It is a square filter ND1000 100x100 mm and 2 mm thick. It allows us to remove 10 light levels to make long exposures in daylight perfect. In the example photo I posted, it is taken at noon at 30 ". I love the play that can be taken from this filter.

The filter comes in a leather case and is covered with tissue paper. The case is sturdy enough to protect it properly.
The glass is not easily marked by fingers and does not attract dust.

The filter holder is metallic, with the part where the filters rest being made of some kind of very hard plastic. They easily fit two 100x100 filters

I wanted a filter holder with these features and an ND filter to start my first steps in long exposure. I chose this brand because I usually like what it offers (and especially for the price it offers, pretty customized)

A sturdy metal filter holder with safety release to put on the adapters and a ND 1000 filter perfect to start taking this kind of photos even in light See in the photos, it comes with a leatherette cover with a soft velvety inside so that the glass and the filter holder do not suffer any damage, although it is presented without cover in the box.

SKU.1878 is a very versatile system and a quality product. The tab filters slide in and out of the holder with ease. So far no light has leaked out. I love that frame for my additional 100 x 100 and 150 x 100 filters get. It keeps fingerprints off the filter.

The company is located in Hong Kong. I would have liked to get extra adapter rings, but K&F Concept doesn't sell them separately, or so it seems. I contacted them through their website/email address and keep getting ads for their backpack. I was directed to get magnetic adapter rings, which are not for this system. It seems if you want to get adapters, you have to buy the filter holder and adapter rings.

This is definitely a product to buy. I look forward to taking pictures with it. It would be nice to have a wide angle sunshade.

I use the product now about half a year, (almost daily) long and am very happy with it!Pro: The installation is easy and holds very well and with the installation rings it is also universally usable for any lens!The filter also keeps its promises and the quality is still excellent!

I have long played with the idea of buying a graduated filter, but the prices of Nisi, Haida, etc. around 150 euros have always deterred me. Then I came across the filters of K&F, since the filter was in a Preislich favorable frame I ordered them.

I had never owned a K&F Concept brand filter before and was pleasantly surprised when I first used it in my landscape photography. The reverse graduated ND filters from the popular brands of photographic filters tend to be quite expensive, and this one in particular is less expensive and produces results equal to and even better than those of the most reputable filter brands. It is made of glass, which is an advantage over resin filters because it does not scratch as easily. I really liked the filter cover, which is made of leather with interior protection. In short, I liked this filter very much and I am sure that I will use it very often in my landscape photography.

Although this is a low cost purchase for camera items, its worth the few bucks! This will be my 3rd lens protector in 20 years. and it just saved my lens once more.

The system is very well built and they sell frames to take advantage of other square filters you have from before.
It comes very well presented, in a case.

Unfortunately, the original box of the product comes with the Amazon label directly attached to it, and opened.
Very bad on the part of Amazon, which sometimes sends cardboard to wallpaper the house with an SD card, and in this case it is worth keeping the original box, they send it unwrapped