Among several domestic and foreign companies offering square filters, I decided on this one because it is easy to put on and take off from the lens, it is thin in the front and back, and it comes with a C-PL filter
For C-PL filters, just open the lid and drop in from above. If you make a mistake in front and back, it will not fit.
The square filter has just the right amount of friction and doesn't feel like it's going to fall off.
Almost all metal, except for the four metal adapter rings and C-PL filter, the holder alone weighs 110g.
In terms of design, the overall impression is sophisticated.

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.

Had screw-on filters for years. Of course they work, but a plug-in filter is really practical, especially for landscape photography. I first bought the filter plug-in system from K&F (Nano x per row). Now have some filters. Filter and plug-in system highly recommended. I'm really excited. Goes fast, good quality and you can also leave filters on if you want to go a few steps further. I also like the frame around the filter. That way, greasy fingers don't get on the filter so quickly. Nothing wobbles. There is also a stylish filter bag.

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.

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.

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.

up until now, square filter holders from other companies have been expensive, and we have endured with SIOTI holders.
I also had an old K&F holder, but it is difficult to use C-PL.
That's where this product comes in. I bought a set of holder + C-PL + ND1000 for the time being, but it is well thought out. There is no vignetting even at 16mm with the Nikkor16-35mmF4, and there is no annoying color cast.
I'm a little worried about the C-PL's adjustment dial squeaking, but I have no complaints at this price with this content.
After that, I would like to see a frame that can be attached to the existing filters sold on the overseas official site, and a filter case that can hold about 6 to 8 filters with the frame attached.
~Addition~
I purchased a 100x150 frame from the US site of K&F. Existing filters can now be used, and full-scale operation is now possible.

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.