For a while I had hesitated between several brands to choose a filter holder for ND and GND filters. I used a flash sale to purchase this kit. I'm not disappointed.
The set is sturdy and easy to store.
The rather pretty body has 5 compartments, 3 of which are raised via a ribbon for square ND filters. There is a belt loop and a belt loop on the back of the case. I would have liked a slightly roomier compartment to house the adapter rings with the CPL filter when that is removed.
The assembly (or disassembly) of the elements is well explained with instructions in several languages, including French.

Main positive points:
No dominant color, no loss of sharpness in the first tests performed.
The plastic frame with its tabs for handling ND filters.
The system for installing the SPS filter on the filter holder.
the knurled knob for mounting the adapter ring and rotating locks the filter holder.
The easily accessible wheel for controlling the polarizing filter.
The stable hold of the square filter on the filter holder.
The robustness of the metal filter holder.

If you must find some negative points: hold
the square filter in the filter holder a little too tightly.
The click is too loud to lock the CPL filter in the filter holder.
No bag to independently protect the CPL filter in the housing.
No protective cover for the CPL when the set is installed on the lens.

The system with the CPL filter assembly beats everything I have used so far. Putting on the bracket is also easy to do. The quality of the filters themselves leaves nothing to be desired. This is how filter photography is just fun!

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

After many reviews that I looked at on Youtube, I decided on the new K&F filter holder and have not regretted it so far. It is easy to use and makes a very high-quality impression. The use of the CPL filter is a great solution. Lever up, put it in and lever down again, done. Adjusting the wheel is also buttery smooth. In contrast to the first K&F filter holder, the filters, which now have a frame, can now be pushed in very easily. Not too easy and not too heavy either. A clear buy recommendation.

Great set of filters for those who cant or dont want to get Lee filters. No colour cast but i would recommend getting some nice pouches to protect them

The buckle holder of the adapter ring is very stable. It is great!

High quality materials, reasonable prices! ! The holder and the filter are contained in two well-preserved and padded boxes. The ring and bracket are made of aluminum. Really nice box! I installed it on my Nikon 5600 with no problems. I will definitely buy more ND filters in the future

It attaches easily and does not allow direct light to enter between support and lens, I am delighted with it, very easy to put on and remove and the filters are of very good quality.
I recommend it for people who are demanding in photography, very good quality.

very good quality. I'm happy.

Very satisfied
Very easy to use system. The picture quality is really good as far as I can tell. The polarizing filter works very well. Thanks to the adapter, the filter can be used on any lens. Have never regretted the purchase.