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.

A few month ago, I started beefing up my camera equipment. I had a Canon 5D Mark IV camera body, but didn’t have great glass. So, I started my gear journey by upgrading my lenses. I now have four amazing lenses including a 70-200, 24-70, 100mm Macro, and a Wide Angle lens. After I finalized my collection of lenses, I started looking at accessories I needed to accompany those lenses and came up with a short list of items that included high-quality filters. The problem I had was that I needed to be able have filters that works with all my lenses. Buying filters for each one of your lenses can get really cost prohibitive. So, one solution I found was to get a square filter with step-down rings. K&F Concept has a great option for this type of set-up so I gave it a try.

About a month ago, I shot photos at a wedding on a mountaintop in Tennessee. It was in the middle of the afternoon and the sun was super bright at the location of the ceremony. The venue was huge and I wanted to pack my camera bag somewhat light so that I didn’t have to struggle with tons of equipment. The square filter set from K&F concept was perfect for this type of work. The kit is lightweight and it makes it possible to use the one filter for several different sizes of lenses. During this wedding I was working with an 82mm lens and a 77mm lens as my primary glass. At the ceremony site, I had to quickly swap lenses and reapply the filter in order to get the shots the couple wanted. I found gaps in the ceremony where I could quietly and quickly change lenses and attach the filters without disturbing the event. It worked perfectly and even though some people might consider it cumbersome, I thought it was a lot easier than having to swap lenses and then screw filter into each lens.

When using these filters, I shot exclusively in RAW, but did not perceive any color cast from the filters. The mount is solid and the filter is well-protected by the soft lining in the case. It’s very easy to attach the mount to the lenses and in my opinion is actually easier to work with than individual filters.

I do feel like the lens adapter could fit a little more snuggly onto the camera lens, but I’m definitely not complaining about that and it is certainly not a dealbreaker. It’s just a tweak that could make the product even better than it already is.

The kit is excellent and fulfill all my needs. Also the delivery time and presentation was excellent.
Very happy with the purchase.

I have been doing landscape photography as a hobby for many years. I used circular filters throughout that time. I had some gift cards and decided to try the square and rectangular filter system. This one was the affordable option. I am happy with the quality of this product. It seems to perform well so far in some of my trials. I will say that the only problem so far has been the carrying case magnetic latch. DO NOT TRUST IT. It will come open if you turn the case upside down. I would rather have had some kind of clip latch or something that is less likely to fail.

I am currently using K&F ND filters, but this time I wanted a rectangular type, so I did a lot of research and decided to go with K&F again! I was a little worried after checking the reviews of the previous old product, which was older than the new one, but the price of the other specialized manufacturer (kani) was too expensive, so I purchased the new Concept Square Half ND Filter Set Soft GND8 + ND1000 Diffuser from K&F. It is sturdily made and has a high-class feel. It's sturdy and looks good. The Half ND + ND1000 filters are exactly as shown in the picture. It has a sturdy frame and I never touch the filters directly, so there are no fingerprints on them. It is totally different from other companies and looks good.

Having some experience with ND filters, I always worry about purple corners or dark spots. I took the set out today and got no strange colors. I love this set, it mounts nicely to my lenses with no fear of it falling off. The picture was taken at 11mm, 13 seconds shutter on my Canon 50D, I found K&F Concept when I wanted a good tripod which I found from them. Now if i need any accessories for my photography i look to them first.

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

I was really looking forward to it, everything is packaged beautifully and with high quality, so you can't say anything really great

This is a very versatile system and a quality product. The tabbed filters slide in and out of the holder without difficulty. So far, no light leaks. I love the ability to get frames for my additional filters, 100X100 and 150X100. It keeps fingerprints off the filter.

The company is based out of Hong Kong. I would have liked to get additional adapter rings, but the company does not sell them separately, or so it seems. I've contacted them via their web site/email address and keep getting ads for their backpack. I was referred to get magnetic adapter rings which are not for this system. It appears if you want to get adapters you need to buy the filter holder and adapter rings.

This is definitely a product to purchase. I look forward to shooting pictures with it. It would be nice to have a wide angle lens shade, but then, you can't always get what you want.

I haven’t had to use it at this point since I use a slow ISO film to begin with. Will use it in the future though I am sure.