All 3 filters for me are very useful. The stand-alone ring however, I'm wasn't sure how much I'll actually use it but surprisingly I just leave it on my lens unless it's pretty bad weather, which in turn I use the UV filter as a protective layer for the glass. Personally, I haven't found the UV filter to do much other than to protect my lens and because the glass of my lens is such high quality I don't leave it on as it could degrade the photos, that's why I use the stand-alone ring. I haven't noticed any degrading when using the UV filter so no complaints. As mentioned earlier, however, I only use it to protect my lens. The CPL filter works wonders and the ND filter is great for long exposer shots. the combination with the magnetic touch make this absolutely flawless. would recommend.

I own quite a few K&F Concept Products. They provide quality products without the hefty price tag we're used to see in the photography world.

Let's talk about the filters individually first. All 3 filters are of top quality, at least on this price point/tier, as we're used to get from K&F Concept products:

-The CPL Filter has no color shifting and performs as expected.
-Same with the ND1000, although i don't use 10-stop filters that often (my most used filter is a VND Nano from K&F Concept) during my test it worked well, no cross present, even while using step-up rings.
-The UV Filter has no color shifting and the main purpose these days of the UV filter is to protect the lens surface, BUT, It is where this VERY MINOR issue this kit has: The magnetic ring holder.

The magnetic ring holder works great with the ND and the CPL, just not as good with the UV Filter, but it is not by ANY MEANS bad or i'd call it unsecure, at least not on the 82mm filter size version, your mileage may vary depending on the kit size you got as the magnetic surface may be different for your version, just the grip doesn't feel as tight as it does with the other two filters and there is a TINY bit of play, but not enough to warrant losing a star over it, i mean if you shake the camera at full strength you may drop it, but on regular usage i do not see it just falling off the ring holder.

As the sum of all parts i'd say this was almost perfect. This kit complements my VND ND2-400 and includes everything i need to cover all my filters along my step-up rings. The UV filter thing doesn't make it lose a star, but maybe half, so i'd say 4.5 but since there's no option for that if i had to decided between 4 or 5 stars, i'll go with 5.

I shoot in various elements and destinations where lighting is different and filters are needed for optimal results. I have been using the traditional screw on filters but I find it time consuming especially how it needs to be aligned perfectly on your lens, taking up to a few minutes for each one when I could miss the opportunity of my shot. I find this K&F filter set to be a great choice for me. I am no professional by any means and take photos for fun with my Nikon d850 and these filters have worked great for me. The magnetic adapter ring is easy to screw on the lens and the lenses stick to it well. These lenses work great in the rain and are not only waterproof but the water beads off of them. I have not had any issue of fogging between the lens and filter.

The come packaged nice in a hard case, each in its own slot. I find this to be a great value for all of the different lenses offered in this set and I am extremely happy with them.

I needed a more travel friendly set of filters to take with me on my hikes that would be too cumbersome to use my square ones. Having these filters in it's own soft pouch was perfect and it didn't take up much room in my camera cube. The magnets were strong as they held on while I was setting up my composition - sometimes in the rain and while on uneven ground.

UPDATE 10/26/21: After over a month, I've already lost a CPL filter. Make sure the filter is flush in either the UV adapter or adapter ring. I was busily setting up my camera on a cliffside when I accidentally bumped my tripod and the CPL filter fell off.

My circular filter kit for each lens size includes a protective UV, a CPL and ND 10 and 6 stop. The K&F kits contain all but the 6 stop. The 6 stop can be ordered separately, though at this time only from the manufacturer's website.

For any given size kit, the K&F Concept magnetic kit costs far far less than would top line individual threaded filters from other manufacturers (Breakthrough Photography, B+W, Hoya HD3, etc.). Yet the optical qualities of these K&F have been tested and are equal to the best. My own experience is that the K&F coatings are also just as effective at repelling water droplets as are my most expensive filters.

Having used K&F Concept magnetic filters in two sizes for a few months I am loving the speed of filter changes and the absence of thread jamming when I stack an ND on a CPL.

My only criticism is the lack of knurling on the front edge of the CPL frame. Magnetic CPL filters do not need or have a two piece construction. The entire filter is rotated in its magnetic attachment, which is fine but remains a two-finger grasping maneuver. To rotate the CPL you'll need to temporarily remove the lens hood. Maybe had K&F added knurling to the from edge a fingertip would suffice, but there is more friction opposing rotation than in a well made two piece threaded CPL. Off course you could attached your old threaded CPL to the lens, screw the open ring magnetic adapter onto the CPL, then add your NDs magnetically. You'd risk jamming the adapter ring to the front threads of your old CPL. I'm not going to do this.

The protective UV is only meant to be attached directly to the lens threads. It is a lens protector. It does not magnetically attach atop the other filters or the open adapter ring. You are give two threaded adapters, one is just an open magnetized frame. The other has the protective glass. The CPL or ND can be clicked onto this protective filter, but not the other way around. My advice is to use the protective UV when facing blowing sand or salt laden ocean mist (and when shooting from a Russian reindeer sleigh where showered by flying feces).

colour-neutral, very easy to use, a significant improvement compared to screw-on filters or the large 100x150 slide-in filters. The included bag is excellent, practical and fits in everywhere.
the polarizer seems better in terms of color neutrality than the expensive branded product from Nisi
The filters fit on the Kase filter holder without any problems. So far I don't see any difference in the pictures. Unfortunately, there was no circular gradient filter at K&F

the magnetic force of the filters is reassuring because strong
the quality of the processing of the nd1000 seems in the standard without colorimetric drift

Well made

Apart from the UV filter that I don't use, I find that the polarizing filter is excellent, and the ND 1000 filter as well, but the brilliant thing is their magnetic assembly, it works smoothly and quickly, an excellent product for me.

There are reviews that already comment on how well they work so I will not repeat, simply say that it is a joy to remove and put on and they are of great quality. The ease of moving the CPL with or without the ND mounted is great. Totally recommended. The only thing is that it would be appreciated to have ND filters of another graduation, an 8 and a 64 for example and put to order, also one of light pollution.