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.

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

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

The rectangular filter is the ideal choice for landscape and architecture photographers.
I myself use a Nikon D4 with an AF-S 24-70 2.8 Nikon lens to test this filter extensively, unfortunately the weather is not that great at the moment but you can already tell a big difference.
Of course you can also say that a simple polarizing filter would be sufficient to be able to display the colors true to nature and without reflections, but with this filter you have even more possibilities to display the horizon more brilliantly. The CPL filter is screwed in behind the rectangular filter and can be adjusted from the lens side using an adjustment wheel with a ribbed surface.
The CPL filter can be adjusted super to increase the exposure time without getting a crossfade of the image.
The rectangular filter holds well in the frame.
With the system, the rectangular frame can be easily removed.

I loved the quality of the materials, all metallic. I looked at many kits but they were all plastic and this one in particular caught my attention from the comments. The truth is that it was a success because any other similar kit does not fall below 300€.The nd1000 optical filter is made of glass and gives a very good quality. The only thing I noticed is that it loses a bit of saturation and the white balance is a little bluish, but when processing the RAW it's easily remedied. You increase the color temperature and saturation and you're done!! (I use a Canon 80d + 16-35 f4's). I imagine each optic will be different. Attached some photos so you can see the difference with filter and without filter. Exposure time on the photo with the 30" filter. If you want to start in the world of filters, for this price don't even think about it. Excellent results.

I received the new X-PRO filter set today and have already tested its applicability in the apartment. I'll give you a verdict on the quality of the filter glasses and how they can be combined in one shot... The box supplied holds the holder + adapter rings + CPL + ND 8/64/1000. You can pull out the compartments on the drawstring and then remove the filters very easily. The plastic filter frames are discreetly sharp-edged, but not uncomfortable, and allow the filter to be removed and handled without having to touch the glass. Thanks to the tabs on the frame, the filters can also be pulled out of the holder very easily, especially in any order. I ordered two empty frames in 100 X 150 from the manufacturer's website, which should hold my graduated filters after receipt, that I have from another manufacturer. I'm curious how well this works. If it works, then I have a complete system for myself, with CPL, three ND filters and two graduated filters (Soft 0.9 and Reverse Soft 0.9). Sliding the filters in and out of the holder requires some force, but isn't awkward or imprecise. In this way, the graduated filter will also be easy to align. The handling of the CPL filter with the insert bracket is great, the turning mechanism is a bit rough, but precise. Screwing the adapter rings onto the lens works very well, the threads are cleanly worked, so nothing rubs. Attaching the holder to the adapter ring is also a joy and the presence of a set screw is very welcome as the holder rotates on the ring with relative ease. The handling of the system has already convinced me, I can live well with "only" two slots for my needs and I'm looking forward to the first use, in the next few days, in the great outdoors and with cold fingers. So far I've worked with round screw filters and dispensed with gradient filters, which I would like to change now. I also looked at the system from Rollei (Mark II), which cannot keep up with the handling of the X-PRO from K+F. Everything is very flat and fiddly, offers hardly any contact surface for holding and assembling the parts. Getting the polarizing filter or adapter ring out of the holder is no fun and almost impossible with cold fingers. K&F solved this much better. If you want to use gradient filters, the X-PRO Set is a good choice, if you only need gray filters,

Once assembled, it works flawlessly For the price, more than okay, but assembly a bit fiddly

I bought this filter set for landscape photography.

Before that, I had been traveling with a screw set from another company. I was then able to screw that onto exactly 1 lens. (I got it for a 24-105).

Experience has shown that screw filters can only be used in part (in my opinion).
If you use an ND 8x filter, you can safely screw it onto the lens and work with it. However, as soon as it gets higher, the camera is overwhelmed. Setting a focus manually, for example, is an impossibility, with a permanently installed 1000x filter.

This set allows you to set up the camera in peace. To compose the picture, to set a focus. Adjust the polarizing filter. When everything is done so far, you can relax and add 64x or 1000x and take care of the exposure.

The whole set is incredibly easy to use. Each filter is placed in a frame, which in turn has special handles.

The set comes in a handy bag.

I don't really want to talk about space requirements. The screw set is definitely more compact, but handling is simply more important to me at this point.
This kit allows me to mount the filters without leaving grease finger marks on the filter. That's worth more to me at this point.

What I particularly like about this concept is the fact that you can now buy graduated filters and the like at a later date and adapt the set as you like it.

After a good six months of use, I can say that the system serves its purpose very well.

Regarding the filters:
The image quality of all filters is excellent and a color cast is minimal even when using 3 filters at the same time. The polarizing filter reliably reduces reflections and leads to a crisp contrast.

Regarding the holding system:
When the polarizing filter is screwed in and the rectangular filter is attached, there is no rubbing, the polarizing filter can be operated perfectly.