The K&F Concept 82mm filter kit has given me a premium, high-quality feel, perfect for anyone who does some photography and video without spending a fortune. I got the 82mm version for my main lenses and use a reducer for my 77mm lenses. At around 50 euros for the three-filter pack (UV, CPL, and variable ND), it's a reasonable price that makes you hesitant to try it, especially considering you get a case that can hold even more filters.

The variable ND filter does its job, controlling light without any issues. It's ideal for shooting video at 50fps, preventing sharpness. If your camera has a high base ISO, you might find it insufficient in a logarithmic profile, but for normal use, it's decent. The polarizer cuts reflections quite well and doesn't vignetting. The UV filter is an inexpensive but far superior product to other competitors at this price point—it doesn't lose sharpness or introduce strange flares. They might have a bit more glare than the more expensive models, but they're much better than the lower-end Kenko and Hoya models that cost similarly or even more. They unscrew easily, come with a very good case, and are very durable.
Everything works as it should.
The drawbacks are minimal: they're not perfect, but for the price, you have few complaints. So, if you buy a decent UV, you get a more than decent ND, CPL, and UV, all with a quality case.
As I said: incredible versatility and decent quality. 100% recommended if you're looking for a solid kit without breaking the bank—you can't find many faults with such a bargain. I'm giving it 6 stars for being so affordable.