I've known K&F for a while now and have one or the other product from them (UV filter and camera backpack). For me, the brand was always technically good value for money and more in the middle price segment.
But now they want to know and are penetrating into the high class area.

A CPL filter is used for reflective environments such as water, panes and glasses or the sky. Exactly these reflections are taken out here and you manage to take pictures down to the bottom even with clear water.
So for me, especially on vacation, it's always a filter.

The filter comes very nicely packaged and is a lot of fun unpacking. Anyone who loves unboxing will get their full enjoyment here.
The filter comes in a cloth/leather bag. Very nice in itself, but in my opinion a filter sits more snugly in the well-known plastic boxes.
The inside of the packaging can be converted into a "picture frame". Funny idea but I think there are nicer ones.

But let's get to the filter itself. Here I have to say again that the performance matches the price and is absolutely justified.
Flawless workmanship, both on the filter thread, ring and glass.
Only the ring is a bit difficult for me personally. If the filter doesn't fit snugly on the lens, it has happened to me that I unscrewed it instead of adjusting it.
The glass is of the best quality and the optical performance cannot be distinguished from a CLP filter from the well-known competition.

In summary, a very good filter in terms of quality and optical performance. It has weak points in the somewhat loose fixation in the storage bag and the stiff ring.
For the price, I really hope that things like this don't happen. So unfortunately I have to deduct a star.