This is an excellent quality circular polarizer and variable neutral density combination filter by K&F. I got the 77mm to cover most of my lenses by using step-up rings. The smallest filter size will be 52mm, seen in the photo. The filter is excellent for all it does and it’s reasonably priced. It’s much more convenient than separate filters; faster to use and less to carry in your bag. Also, this will work with some wide-angles that would be a problem when stacking multiple filters. The build quality of the filter is excellent. A leather storage case is included. There’s some very slight vignetting and color shift starting at 4 stops which increases with more ND filtration. That is expected and can be dealt with in post processing if desired. Image clarity and sharpness is not affected. This filter outperforms other CPL+ND filters I’ve used.

Really nice 2 in 1 variable ND and CPL filter. The inclusion of the two putters makes it exceptionally easy to make adjustments one way or the other, depending on what you're adjusting. Turning the filter clockwise changes the density between ND4-64, while turning the filter counterclockwise adjusts the polarizer effect.

I find the 6 stops between ND4 and 64 to provide a very versatile range that works for 99% of the things I'm shooting. The adjustment is smooth, and the density changes evenly and consistently throughout the entire field of view.

The polarizer adds much needed functionality and eliminates the need to stack an additional CPL on to the ND filter.

I experienced no color shift or vignetting while using the filter.

Filter comes with a nice storage case as well.

This is the variable ND filter and polarizer.
The CPL filter eliminates light reflections on surfaces, cars, water, glass, and also enhances the colors of the sky, leaves, asphalt, etc.

I personally use it for video so I don't lose depth of field by closing the aperture (from f9 I can now go to f2.3 without burning the images due to too much light).

About the image quality. Well, excellent: There are no dominants, no chromatic aberration, no loss of sharpness or the horrible X of gradual ND filters.
I have a very expensive polarizing filter and hardly notice the difference with this one.

Price and performance are top !!!

Great Variable ND Filter for the price

This is a high quality circular polarizer variable neutral density combination filter from K&F. I used the 77mm to cover most of my lenses using step up rings. The smallest filter size is 52mm as shown in the photo. The filter is excellent for everything it does and it is inexpensive. It's much more convenient than separate filters; it is quicker to use and requires less carrying in your pocket. This also works for some wide angles, which would be a problem when stacking multiple filters. The build quality of the filter is excellent. A leather storage case is included. From 4 stops onwards there is a slight vignetting and color shift, which increases with increasing ND filtering. This is expected and can be fixed in post-processing if desired. Image sharpness and sharpness are not affected. This filter outperforms other CPL+ND filters I have used.

K&F combined a circular polarizer with a variable neutral density filter to come up with this excellent 82mm variable fader and CPL as they call it. The 82mm size fits most of my Nikon Z lenses.

It is easy to adjust using the two red opposing tabs on the barrel. A beautiful professional filter at a fair price

As a filter, for both polarizing and variable ND, this is a solid 5 stars! I'll explain 4 stars to get this out of the way—the filter is large in diameter, and those orange grips stick out even farther. This will not allow any of my lenses that use this size filter use their lens shades at the same time. Also, (and this is probably necessary, to avoid vignetting), there are no receptical threads in the front—so you can't use your lens cap when the filter is attached. I have a feeling that this larger diameter is an issue with most variable ND filters though.

Now that those issues are out of the way, I can speak to the positive attributes. I have a number of very good polarizer and Neutral Density filters (none combined) from top manufacturers. I've avoided variable ND filters in the past—pretty much every review I've read mentions an "X" that appears (as a darkening) once the filters are above 3 or 4 stops. But, since I've used several of the higher grade K&F filters (UV and ND) and have seen how good they are, I thought this one was worth a try.

First the polarizer. I've attached two birdbath photos—one without and one with the filter at maximum effectiveness (with the ND set at 1). (Note that without the polarizer, I was focusing on the reflection on the water surface, so the birdbath and surroundings are out of focus. This also affected the overall exposure.) To my eye, this is working very well, without creating undue color casts, and the exposure is even across the image.

Next, the ND The first shot is no ND filter at all, and the second shot is the maximum 5 stops of this filter. There is a very slight color shift between the two; it's possible that if I didn't have color temp. set to auto on my camera, the difference might be more apparent—as it is, the correction needed would be easy in post. The main issue to me, is that the color shift is even across the image. And, the only ND filters that I have (and remember they are fixed ND, not variable) that have less color shift than this cost more than this filter. (And, they are just a single ND and there is no polarizer in them, either.)

The filter comes in a very nice case; I'm undecided if I like this better than the typical top and bottom lock together "caps" or self hinged snap box that all my other filters come in. It doesn't take up more room, and it's fun to pull the orange webbing and watch the filter lift out of the case.

This is a very well made and packaged K&F filter that offers both a circular polarizer and variable neutral density functionality in a single 77mm package. Build and thread quality is top notch. K&F packages their filters so nicely and includes a solid carrying case. Recommended.