I loved the quality of the materials, all metallic. I looked at many kits but they were all plastic and this one caught my attention especially from the comments. The truth is that it was a success because any other similar kit does not fall under 300€.The optical filter nd1000 is made of glass and gives a very good quality. The only thing I noticed is that it loses a little saturation and the white balance is a little bluish, but when processing the RAW it is easily fixed. You increase the color temperature and saturation and you are done!!! (I use a Canon 80d + 16-35 f4 is). I imagine each lens will be different.Attached a few 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, do not even think about it for this price. Excellent results.

I bought this because the kit provides me with the variety of filter mounts I need to cover my lenses. I have not seen any problem with unevenness or color streaks in my images. Focusing is a challenge, of course, due to the filter density. The mounting rings attach securely to my lenses and the connection between the rings and the filter holder is solid. My filter fits firmly in the holder. I suggest inserting the filter into the holder "off camera." Screw the appropriate mounting ring onto your lens, and then "click" the filter/filter holder combination into place. While still holding the camera in one hand and the filter holder in the other, try to wiggle it or pull it off to test that it is firmly attached and that it won't fall off while you are shooting.

excellent filter system. Very easy to use. Ordering from k&F Concept is easy. Highly recommended.

To be honest I was really hesitant to purchase this, however the price intrigued me enough to give it a try. I have to say this ND Filter is right up there with the best. It comes nicely presented and the case to store it in is great. There have NOT been any weird coloration in. The glass is high quality and easy to clean. Honestly I love this ND Filter.

I got this for the filter holder and adapters. They work great!
Mad the filter that came with it is pretty decent.

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

Main positive points:
No color cast, nor loss of sharpness on the first tests carried out.
The plastic frame with its tabs to handle the ND filters.
The system for placing the CPL filter on the filter holder.
the knurled knob for mounting the adapter ring and the rotating housing of the filter holder.
The very accessible wheel for controlling the polarizing filter.
The strong hold of the square filter on the filter holder.
The robustness of the metal filter holder.

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. The compartments can be pulled out on the drawstring and the filters can then be removed 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, which I have from another manufacturer, upon receipt. 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, I would recommend a magnetic round filter set with a diameter that is significantly larger than your largest lens, which is even faster to use, is more compact and should then do not darken with several filters in parallel.

Finally found an ND filter which can be installed inside the Smallrig lightweight matte box 2660. I did have to remove the holder frame to make it fit. This can be done by carefully pulling appart the frame sides with the lips. In doing so you can op out the filter while keeping the frame intact. Filter quality seems to be ok and it comes with a very well designed holder with an extraction ribbon which avoids having to touch the surface of the filter when taking it out.

Love the rapid release frame and the secure fit of the CPL, along with the easy rotation. No evidence of colour cast when stacking filters. Carry case is good quality also.

The filter set. The filters are individually in a beautiful leather case, with magnetic closure and labeling card have a good color fidelity, I've tested them all a few times and I'm satisfied.
Purchase recommendation from me. (especially with the offer, with all the adapters + 4 filters it's always better, but that's good for me too) it's fun with it. With this offer, the price-performance ratio was great.