The variable filter comes in a high-quality and beautiful packaging, which is of course also perfect as protection for transport.
The rotating adjustment between ND2 and ND32 is practical and especially good for travel, as you don't have to use several filters. If the ND32 is sufficient to reduce the light, the filter is perfect.
Especially for landscape photography: just turn the strength as needed.

I recommend it - also for beginners who want to try it ;-)

Bought for videographic use, a must if you shoot in V-log. The magnetic anchoring system is excellent if the filter is placed properly: to place it, it is necessary to fit it in its notch; to remove it, it is enough to unhook it from the magnetic ring. In any case, it is a very quick operation. And there's no need to remove the protection filter either (it's true that I use completely neutral Sigma filters, without UV protection). It can even be used with the butterfly-type hood of the Lumix 20-60 on my Lumix S5. The handling becomes a bit more difficult, but you gain in comfort when attaching and removing the filter (for example, in transit from a bright exterior to an interior).
There are no significant aberrations, which is surprising for an inexpensive variable ND filter. Obviously this is influenced by the ND2 to ND32 scale, which is very short for this type of filter. Highly recommended

This magnetic filter set is ideal for quick access to the most useful filters. Simply screw the magnetic ring onto the lens and the filters stick to the ring.

The ND filter was great on bright days to keep exposure under control. Note that the ND filter is quite intense, which is great for sunny days, but sometimes too dark for cloudy or night shots at certain settings.

It can be easily attached to your camera bag or belt when shooting in bright light.

High quality product. The filters fit perfectly. They do not fall out even with the weight of the lens cap.The filter fits perfectly. No vignetting with my Nikon 24-70mm lens either. I am very happy with this filter system. Innovative.

There is no loss of quality and also no spot darkening.

The price is ok.

I bought a larger filter and an adapter so as not to have unnecessary filters.

Super performance for little money.
The ND filter comes in a very good quality transport box.
Quickly and easily you can adjust the degree of darkening so that it gets everyone.
I had to try it immediately and was thrilled.
I can only recommend the ND filter.

I really like the convenience of this magnetic filter system. You just have to thread onto the base ring and magnets do the rest.
Each of the filters themselves are slightly heavier than the bolt on K&F versions, probably because they have to make the filter ring out of a magnetic steel instead of aluminium. Whatever the reason, they feel a lot more premium than the regular K&F version.

On the bright side, there's the obvious: it's quick and easy to be able to switch between the three included filters. Attaching the filter adapter is easy and selecting the filter (or selecting a filter) really only takes a second or two.
In short, the individual filters are great as far as filters go.

I often photograph in a wide variety of lighting conditions and like to take long exposures in between, and so far I have always had to take several ND filters with me.
Changing filters was always a bit annoying, so I decided to use this variable ND filter. The filter is variable from ND2 to ND32, covering a wide range of usage.
I also couldn't see a dark "X" as a shadow in the image (which can be caused by the overlapping of two layers) and also no color cast with this filter.
Great value for money!

K&F Concept Nano-X variable ND with thread vs. K&F Concept Nano-X Magnetic vs. Freewell variable ND with thread

Looking for a variable ND filter for wide angles up to 24 mm focal length (APS-C 16 mm) I have the three filters ordered from amazon.de. Since prices are constantly changing, I just want to name the order. The K&F Concept Nano-X ND with thread is the cheapest, the K&F Concept Nano-X Magnetic is the middle priced one and the Freewell with 77mm thread is the most expensive.

I took photos with the 3 filters on the brand new Nikkor Z 4 / 24-120 mm and the Fujinon 2.8 / 16-55 mm.

The darkening of the K&F Concept Nano-X ND and K&F Concept Nano-X Magnetic are identical. The Freewell starts with a slightly stronger darkening. About 1/4 stop or time.

The 3 filters differ significantly in terms of vignetting (dark image corners). The K&F Concept Nano-X Magnetic performs worst on the Nikkor Z 4 / 24-120 mm with a focal length of 24 mm (see photo). If it absolutely has to be magnetic, I would go for a larger filter diameter and use a reduction ring. The K&F Concept Nano-X ND vignettes a little less (not at all on the Fuji 2.8 / 16-55 mm). The variable ND filter from Freewell achieves the best vignetting results thanks to its very flat design.

I find the K&F Concept Nano-X ND best packaged for transport. Here you get a nice round box with snapper. I liked the square plastic box from Freewell the least, but you can buy a very good (artificial) leather box with a zipper for a total of 5 filters from Freewell.

I am happy if my contribution is considered helpful and makes the decision easier.