Have now used the filter in a wide variety of situations and can only say that it is great. Top picture quality and the protection is perfect. Use it on my 24-70 2.8 Art from Sigma on my A7 III. The image quality is not compromised and the lens is perfectly protected. The processing is very good and of very high quality. Completely happy.

These are so easy to use and the quality is fantastic - both build quality and picture quality. I can't see any color cast from the ND filter. I think you'd have to be really pixelated to see a difference in sharpness, and even then I'm not sure there is.

There are reviews already commenting on how well they are doing so I won't repeat it just say it's a pleasure to take off and great quality. The ease of moving the ND filters mounted or not is great. Highly Recommended.

Great UV filter that adds nothing to your photos. No color shift, no bluish cast, no blurring... nothing. Just a crystal clear UV filter so you can rest assured your lens is protected. The slim design is nice because it doesn't produce vignetting. This quality is unbeatable!

I liked the fact that they are magnetic because it's much quicker to swap or remove one for the other without having to screw them on.

They are of good quality and reasonable price.
I've tried the variables and it looks great.

The ND 128 is also very suitable for long exposures.

In summary, I liked that the system was able to change the filter so quickly when I was traveling or in awkward situations, I would appreciate it.

The filters are great and can be changed quickly. colour-neutral, very easy to use. The included bag is excellent, practical and fits in everywhere.
The filters fit on the filter holder without any problems.

I have a long history of shooting with special effects filters. I've used Cokin systems where you can share a filter with different lenses using adapters. I own over 50 such filters and lately I've been simplifying my camera bag and traveling with just a few filters. My favorite filters are the Graduated Neutral Density (ND) filters. With these, I can rotate the filter to my liking for each shot. BUT it means I have to wear more than a pair of the same ND filter but on different stops.

Solution: The K&F Concept magnetic variable ND filter gives me the opportunity to use a filter that covers 5 stops within seconds. This is a great time saver as my landscape or sunset shots sometimes require quick image setup and adjustment to rapid light changes.

ND filters are an investment in your camera equipment. These filter out very bright light and enable the photographer to take longer exposures in daylight. My favorite use of ND filters is to make water movement look silky while still capturing the surroundings in detail. This K&F Concept filter is amazingly well built. The glass is better than my cokins. Because it's built for specific lens size diameters, I had to rationalize which lens I used most often and order that size. 58mm in this case.

The housing is a worthy vault for this filter. Kudos to the team that developed this feature. The magnetic ring screwed well into my existing lens. In fact it screwed in too tight, it took me 10 long minutes to unscrew it later.

The magic is in the magnet technology. Wow! It was instant on and instant off for the actual ND filter. Great. With that comes the fear of dropping the filter. I'm afraid a bump will loosen it, so I kept my hand on the lens the whole time. If you're in a stationary environment, you should be fine.

This lens filter is a great tool for many future vacation shots. Easy to carry and use.

Note that you cannot place a regular lens cap over the ND filter. Too bad.

Overall, I love the new direction these ND filters are taking. There is less effort and more time is spent on actually capturing images. Try it. I recommend this variable ND filter. 4.5 stars.

The filters are of excellent quality and leave the adapter ring fitted. If necessary, they will be deployed in a second.
The filter housing is also excellent.
I will also buy the CPL filter which is not included in the kit but I am waiting for a discount.

How strong is the magnet?
Once attached to the lens, even if you walk with the camera in hand, you won't lose the filter, so don't worry.
►Overall experience?
Impressive technology!!