The filter is nice and flat, the glass is impeccable. The screw thread fits perfectly into the thread of the lens and the lens cap grips easily. I could not determine any distortion of the colors in comparison shots. I use it to protect the front lens; I hope he lives up to his intended task.

The results with the filters are outstanding and I am absolutely satisfied with the image quality that you get with them. All the colors are even and come out great. With a little practice, you can get almost professional pictures even as a hobby photographer. It is definitely helpful that the entire equipment is very light, compact and handy, which makes it really easy to transport and take with you on the go.

I took these filters instead of others I already had (always bought K&F Koncept here) to have something practical, comfortable and light with me that adapted to my new philosophy for outdoor and family needs (functionality and lightness ). What I discovered was a wonderful surprise. In addition to being practical, these filters and the case with which they arrive are of good workmanship, have good optical rendering and have no chromatic aberrations. For me they represent a real REVOLUTION.

High quality glass with excellent ND filter performance. Turning the filter too far will not have an "X" due to the hard stop built into the design.

The kit includes a magnetic adapter ring that screws onto your lens and acts as a mounting tool for the ND filter - just toggle it on and off whenever you want. very pleasant.

It is important that the filter itself offers a wide range of densities with minimal color shift.

The slim design is great and does not cause vignetting with regular use.

Overall, a great filter will deliver consistent and reliable results.

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

The K&F D-Series UV Filter is a well-made, durable optical device that appears to perform as advertised. I wish I had noticed that the NANO series filters are a little better and only a little more expensive. If you compare this D series filter directly to the B&W UV Protection Filter (010) (XS-PRO), MRC Nano, the K&F product certainly seems to be of the same quality and performance for less than half to be of the price.

The price is surprisingly very cheap than other brands, you really get a lot for your money here. All parts are very clean and tidy and make a very solid and high-quality impression. Of course, you still have to decide whether it's worth the money.

Conclusion:
Really great system and high-quality workmanship but also an expensive price.

These new filters, with their magnetic attachment, are assembled and disassembled in a fraction of a second (see attached video). They are ideal for family outings.
The magnetic attachment represents a real REVOLUTION.

I've wanted to try these K&F Concept Magnetic Filters since they were announced.
I'm glad I bought these. They are great,
super easy to use and swap out in the field. Simply attach
the magnetic ring to your lens and then it's easy to attach and swap out the filters easily.
No hassle of having to screw the filters on and off, this is totally a game changer in my opinion, I own a bit of K&F gear and these are great quality as always,
They don't come cheap but you get yours, what you pay for, i am very happy overall

I'm really excited about these new filters that K&F are releasing. The magnetic filter system is a great idea for strong ND filters as I often have to compose my shot without the ND filter attached (because without it it's much easier to see through the lens) and then have to attach it to take the shot . Being able to easily snap the filter onto the front of the lens takes a lot of effort out of removing and reattaching the filter.

The optical quality is excellent, with excellent clarity and hardly any color cast. The processing quality of the metal rings is solid; They are smoothly machined with smooth edges and beautiful knurling. The rotating ND filter rotates smoothly, with hard stops at both ends of the spectrum so you'll know when you've reached the limits.

The magnetic attachment keeps the filter firmly in place, but is probably best used in controlled tripod setups where you know the lens won't be bumped. I definitely wouldn't use this in mass situations where someone or something might knock the filter off, as it wouldn't take much of a jab to make that happen.

No lens cap is included, presumably because the extra weight would make the filter too heavy for the magnets to comfortably hold. K&F makes a magnetic lens cap that I got with another K&F filter set, but it doesn't fit on the outside of the ND filter because the outer ring is larger than 77mm. However, the magnetic lens cap fits on the inner ring, so you can use it when you don't use the ND filter. As far as I can tell, you can't buy the magnetic lens cap individually, only in a bundle with other filters.

The quality of this filter is quite comparable to that of Tiffen. It's reasonably priced and I would definitely recommend it for tripod landscape photography.