During the window test, when we set ND to the maximum value, I didn't notice X.

It is a variable and polarizing ND filter.
The ND is 5 steps, there are 2 steps, 10 steps (ND1000, 1024 to be exact).
The polarizing filter eliminates light reflections on surfaces, cars, water, glass and also enhances the colors of the sky, leaves, asphalt, etc... (for more information search the web) Personally, I use it for video so as not to reduce the depth of field by closing

the Losing membrane (f9 further, I can now go to f2.3 without burning the frames from excess light). Haven't removed it from my 35mm in a while, I love it.

The filter is made of metal and glass, presented in a hard plastic case for storage. The protective and anti-glare layers of a greenish color are appreciated and you can put the lace on top that holds quite well without staining.
The lever changes the density of the filter and the other ring moves the polarizing filter. You need to pay attention because you can move both carefree.

In the pictures you can see the filter attached to an adapter, (Step-Up 49mm to 67mm) this is because I have filters of 67 and 49, my advice is to buy big filters and then "Step-Up" adapters.

About the picture quality. Excellent: There are no dominants, no chromatic aberration, no loss of definition, no appearance of the gradual ND filters' terrible X.
I have a very expensive polarizing filter and I hardly notice the difference with this one.

As a negative point, although I said before, be careful when handling one of the rings so as not to move the opposite.

**If it was helpful to you, remember to upvote so we can help each other** :)

My choice fell on Polar Pro or K&F. Well, now I know the answer! This filter exceeds my expectations! The high-quality processing is PRO. You'll see when you run this filter on your lens, after all I don't need two separate filters on top of each other. From now on, I've stopped buying cheap filters, especially if you have a loan that costs over $1000. K&F did a great job here and for the price it's fantastic!

I use the neutral density filter for my nature photography and landscape photography. Especially when photographing rivers, lakes or waterfalls, this filter, thanks to its variable darkening from ND2 - ND32, offers an extension of the shutter speed, which results in motion blur, which looks very nice with watercourses. In addition to the ND filter, there is a second filter function, a CPL polarization filter. This is very practical when photographing water, lakes and streams, as reflections can be compensated for at the same time. I chose the 77mm filter variant and use the filter on a 12-24mm wide-angle lens. The processing quality is very good, even with maximum dimming of ND32, the unwanted X effect does not occur.

Works great, has smooth action, and kills two birds with one stone by being able to spin and kill reflections. The only complaint is incompatibility with many lens hoods, but well, it's better to reduce the diffraction and hit your target than eliminate the diffraction and have to jump through hoops to get a decent shot.

Very easy to use and produces high quality images. Being able to adjust exposure without removing and adding filters makes shooting so much faster. Image quality is great.

The filter is supplied in a plastic carrying case with high quality foam for protection. The filter sits firmly in the housing, so you can be sure that it will not move after storage or be damaged during transport.

The filter itself feels of good build quality, with the metal frame holding the glass in place. I like the lever to adjust the stops, the action is smooth and doesn't move on its own. I would have preferred that K&F included a lens cap just in case I wanted to leave the filter on the camera.

Pros: Great packaging, clean glass, no color shifts.
saves a lot of time on run and gun shots. especially with gimbals

Cons: requires practice to turn it with one hand. Just remember to turn off your gimbal motors before rotating the filter or you may damage your gimbal motors.

I love that this is a combination of variable ND and polarizing filter. It makes setting up my shot so much easier without trying to put two different filters on. In addition, this filter feels and looks really solid. Another important thing is that this filter doesn't have that pesky "X" that some others have. I would recommend this and I think it would be great for anyone who wants a decent ND and polarizing filter without spending hundreds of dollars.

The very experienced photographer who found this and recommended it to me as my first filter, but he also bought it and loves it - it's his filter now