K&F concepts. They’ve been around for awhile now, so I trust them and their camera gear.
As far as their UV filter, it’s awesome.
The packaging itself is beautiful. The box it comes with actually turns into a frame for a photo that you can place into the center of it.
The filter case is also beautifully made. Really premium feel. The package also includes a cleaning cloth.
But the filter. First off, putting it onto my lens was pleasant. The partially texture/knurled surface of the ring makes it putting it on and off easy. You can really get a grip onto the filter.
The clarity is way better than my previous cheap Hoya. This might be due to the different coatings this filter has but it’s been noticeable.
I mainly use UV filters for protecting my lenses. I’ve had a few drops and I’m always happy that I’ve had a UV filter on.
You don’t want to cheap out on a UV filter because it may affect image quality and I’m glad I’ve got this one from K&F. I’ll be leaving this on this lens forever!

I'm comparing this item KF's regular Nano filter. At the same settings on my Panasonic 85mm f/1.8, I can see more detail coming out of my lens on this Pro filter versus the regular Nano Filter.

Since I love the sharpness of the 85mm, I'd much rather use the sharper filter. It's probably not a big deal to those who aren't pixel peeping but I can definitely see a difference in the hairs and I really like this filter.

Filter is nice and I would recommend this product

is reviewed:

"K&F Concept Nano-X PRO Series UV Filter 77mm, Slim Flagship MCUV Filter Protective Filter"

The filter came well packaged in elegant outer packaging. Even this made you curious about the filter with its exclusive appearance.

After opening it, you can see an elegant, very cleanly crafted leather filter protective cover.
This has a folding mechanism that closes safely and cleanly using a magnet.
There is a fabric flag on the side of this protective cover. If you pull on this, the filter comes partially out of the cover via the pull-out function, so that you can remove it very easily and without risk of damage. The filter is packed in a foil bag when delivered. There is also a microfiber cleaning cloth inside the packaging.

After completely unpacking, you can attest to the filter's high-quality and clean workmanship. The filter is free of processing or material defects. The thread of the filter can be screwed onto the lens very easily. The manufacturer specifies 0.01 mm processing accuracy. You can feel this when assembling it. There is absolutely no wobble here. This means that neither wide-angle nor telephoto lenses are affected in their original performance.

Everything works perfectly. The result is impressive.
From now on, my high-quality telephoto lens will be very well protected and, thanks to this UV filter, which guarantees 99.9% light transmission, it is optimally equipped for fantastic shots without any loss of image quality.
The filter has a double-sided 36-layer nano coating. The 0.15% reflectivity of the filter ensures the above-mentioned good light transmission. This reduces stray light very well and prevents further glare. The filter is also waterproof, dirt-proof and scratch-proof. The filter is also extremely light with a very thin brass frame. The type, manufacturer, function and serial number of the filter are noted on this.

Conclusion:
A high-end filter from K&F that impresses with extremely good workmanship and high quality.
Clear purchase recommendation despite the very high price.
I rate the product 5 stars.

Thank you for reading my review, I hope it was helpful to one or two people.

Objectively speaking, you might ask yourself what exactly justifies this price: a filter that many photographers only use as "lens protection" and whose effect is usually not even visible in the photos. But this line of thought falls short in my opinion.

The Chinese manufacturer K&F (or Kentfaith) is no longer a cheap provider. The product range and thus the expertise includes not only UV filters but also other filters (CPL, NDF, etc.). This filter therefore comes from a group that puts a lot of thought into how to build even better filters. And you can tell that from the packaging of this X-Pro filter:

I ordered the K&F Concept Nano-X PRO series UV filter to use with the Pentax HD DA★ 11-18mm F2.8 ED DC AW lens. I usually use my high-quality lenses without a UV filter. Ultimately, any additional glass in the optical path degrades the quality. But in dusty weather or when it's raining, using a UV filter is definitely a good idea, as you can then rub the filter dry with a cloth or remove dust. If the filter gets scratched, the front lens of the lens is still undamaged.

Now for the filter. The K&F Concept Nano-X PRO series UV filter comes in quite elaborate packaging. The filter is in a pouch, parts of which are even made of real leather. The closure is magnetic. There is a strap on the side of the pouch. If you pull this, the filter slides out of the pouch.
A cleaning cloth is also included in the delivery, and a cardboard stand (?). I don't really understand the point of this. Perhaps it is intended for presentation purposes for dealers?
The filter is "Made in China". There is an importer's address from Germany on the box.

The filter can be easily screwed onto my Pentax HD DA★ 11-18mm F2.8 ED DC AW lens. There is nothing to complain about. The Pentax HD DA★ 11-18mm F2.8 ED DC AW lens is not shaded by the filter. The filter's workmanship is also really good.
I took a few test pictures with and without the filter, and could not see any negative effects. Under normal conditions, I don't think the image result will really deteriorate. Perhaps there are problems with light reflections in backlit pictures when the sun is at the right angle. But that would be a general problem with filters on lenses.

Conclusion:
The filter is really good. The current price of €149 for the 82mm filter is certainly anything but a bargain. Ultimately, it doesn't make sense to buy a lens for around €1500 and then screw a cheap filter onto the lens, which then leads to poorer image quality. I give the filter 5 stars.

If I'm honest, I've always relied on established brand manufacturers such as B&W or Rodenstock for filters. I do have a few filters from Kase and K&F in my inventory, but I hadn't really considered Asian manufacturers when it came to filters.
And that's exactly what K&F wants to change with the Nano-X Pro series

its hard to believe, but this is the first UV filter that I have had that actually makes my images BETTER! Most UV filters I have used over the years have had no real real visible effect on my images, and some have actually had negative effects because of poor quality. This filter is seriously amazing to me. It better be for the price, right?! Lol. its pretty expensive, but my images are actually coming out better with it, so I guess its worth it. Loving everything that is coming out of K&F Concepts lately. they have really stepped up their game.

The lens looks and feels nice. It seems to be of good quality and would last longer. The storage case looks elegant and comes with a wipe to clean the lens. The few pictures I have taken seem reasonable, and the lens doesn't cause any issues with the quality.

I am new to photography so my experience is limited. The photography store I go to told me to be careful with lens covers as they have had a few people come in with issues with their camera not working and tracing the issue back to a bargain brand lens cover that was bought online. I showed them this one and they said it should be good to go.

We have now bought two different sizes for different lenses in this brand. Acquiring the first one in December and the second in February. Both work well and help with stage lighting glare.