"We have what would be several filters (actually more than 2) in one. And I say several because there are ND (neutral density) filters with different degrees of darkness. Here we can regulate it. And the same filter with a function of polarization.
Below I explain what each thing is for (for people who are amateurs or not initiated in photography or video).

The filter itself is well built. It's quality. It works well (I mean smoothly in all its movements and turns, without strange sensations or suspicious noises, it twists well). It weighs its own. It is well thought out.
Good presentation. Robust case to be stored carefully.

Comes with a microfiber cloth (always appreciated).

AS A NEUTRAL DENSITY FILTER: so that we understand each other, it is like putting “sunglasses” on the lens. When we want greater darkness than the lens (and the camera) can offer us. For example, let's imagine that we want to photograph a waterfall at slow speed to obtain a “cottony look” of the water. If there is a lot of light, with the camera and lens settings it will be impossible to shoot at low speed. For that, for example we use neutral density filters (also called ND). We can use them for other creative purposes to suit the consumer. But that is essentially its function.
About this neutral density filter: very curious. We adjust it to our liking (see video) and we don't need to carry different filters (of different degrees of darkness). Very good.

AS A CIRCULAR POLARIZING FILTER: circular to differentiate it from the linear polarizing filter (but it would be excessive to explain it). It essentially serves to saturate the colors by choosing where. As we rotate it (that's why it is circular) we can observe how it saturates in different areas. It is very practical to assemble it, look at the sky and rotate to observe how the color darkens and intensifies in the area we choose depending on the rotation. Very useful in photography to saturate colors (especially skies, seas, etc.) and give them color intensity.
Other use: to control (suppress) reflections. In my video you can see that depending on how I rotate it, I add or especially remove reflections. This is seen in water, for example, in glass or on reflective surfaces. I strongly encourage you to try it because it is surprising how reflections are suppressed.
About this polarizing filter: it behaves acceptably well (not optimally, perhaps it could be stronger and more homogeneous in the transitions, but it does its job). It costs a little to turn (but nothing serious).

Let's keep in mind that with the filter on we will not be able to attach the lens hood to the lens. This can be seen in the small aberrations (spots near the sun) in the images I have taken. It is not the direct fault of the filter (it is caused, in part, by not being able to put the parasol on...although looking directly at the sun, the spots will always appear...and there are even those who love those light effects).

Let's go to the summary?

I am an amateur photographer and in no way my opinion is professional. I have always been amazed by what filters can add to your photography game but the need to change between filters plus cost made trying them a challenge.

This filter seems to answer these concerns, it is multiple filters in one so no need to swap filters, just rotate to your choice.

The quality of the pictures is hard to judge since it is winter time and no sun light to filter, saying that however I don’t see any black crosses or distortions.

As for the price, it is reasonable. Almost the price of one filter.

Combining an ND filter and a Circular Polarizer in one filter is such a helpful filter, there's almost no reason to remove this from my lens, unless I am shooting indoors. Having both in one filter and being able to dial both in separately is such a good tool and accessory, it is really amazing for using when shooting outdoors in bright sunlight, for being able to lower the f-stop to get my aperture low and get those wonderfully creamy blurry backgrounds, and also dialing in the reflections off of the water, or enhancing the skies. This filter is quite a bit larger than most, and is definitely not a small thin filter, but the glass is great quality, and the threads are machined perfectly. I have no complaints about this filter at all and am really happy I decided to order it. It will get a lot of use from now on.

Ive been a fan of K&F for a while now. They put out high-quality products and never disappoint. This filter is no exception. Built-in CPL with ND2-32 is great. Since it is so versatile, this filter will live on my lens for a while.

"The product is an ingenious lens because it combines two functions in a single device: it acts both as a neutral density filter and as a CPL filter.

The CPL filter, or circular polarizing filter, is a type of filter used in photography. It is used to reduce unwanted light reflections from non-metallic surfaces such as water or glass, making colors more saturated and the sky bluer. Additionally, it can help improve the contrast and sharpness of the image.

The ND2-32 filter is a type of photographic filter called a neutral density filter (ND stands for “Neutral Density”). This filter reduces the amount of light entering the camera lens without altering the colors of the scene. It is particularly useful for shooting in bright light, allowing longer exposure times or wider apertures. The number ""2-32"" indicates the neutral density range of the filter, giving you the flexibility to change the density based on lighting conditions.

The ND filter can help in these situations:

1. **Photographing Waterfalls or Streams**: The ND filter helps reduce the amount of light entering the lens, allowing for longer exposure times. This can create a silky effect on the water, making waterfalls or streams choppy and smooth.
2. **Shooting in Bright Light**: In bright light, the ND filter can help control the amount of light entering the lens, allowing the user to use wider apertures without overexposing the image .
3. **Photographing the Sky**: During the day, the ND filter can help darken the sky, allowing you to capture cloud details that would otherwise be overexposed.
4. **Outdoor Portraits**: The ND filter can be useful for outdoor portraits in bright light. It allows you to use longer exposure times or wider apertures to achieve a shallow depth of field, keeping the subject in focus and blurring the background.
5. **Architecture or Cityscape Photography**: The ND filter can allow you to eliminate moving people or vehicles from a scene, creating a clean, non-noisy image.

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This is a great variable ND and CPL filter that works very nicely. It Is an ND2-32 variable and circular polarizing filter. When attached to my lens and texted through the ND range there was no notice of the "X" pattern that can be noticed in some cheaper quality variable ND filters. the ND rage is effective for general photography and should prove useful in any photography kit bag. there are two small "handles" that makes for easy rotating/adjusting of the ND range but I do prefer a design that doesn't have the handles as it's a little more compact and can be kept on your lens without worry of catching the handles if you are putting your camera in a bag and removing it frequently or quickly. That said, there is some merit to the handles as they make for smoother adjustment. It's all to your preference. The polarizer comes in a nice plastic holder with good foam to keep it safe from damage. The 24-Layer waterproof coating and 5 Stop ND Polarizer is a nice combination particularly for landscape photos. All in all this is a great variable ND filter that I wil Ladd to my kit to compliment my other filters. I would recommend it.

People have claimed you can't put the lens cap on this. For the 49mm at least my OEM canon lens cap went on just fine.

It JUST fitted under my glare shield but I can't remove the shield without taking off the filter first.

I can still access all the functional parts though as things like CPL and ND are only really ever changed in a gradual manner on a fixed tripod so I wouldn't ever need to rapidly change it and thus don't need super easy access, but without the shield on this is very easy to quickly adjust.

Worth every penny for what combines about 5 potential different filters into one unit. Very happy as always with K&F

Bought specifically for my "light travel" camera so I wouldn't have to cart around and fiddle with multiple filters. It does its tasks well enough for its price point, but unfortunately has some downsides. The main one being a sharpness issue. I initially thought it was my lens or camera since I recently bought both and hadn't had a chance to really test them out yet. Then I decided to double check the pictures I took right *before* using this filter, and sure enough they're noticeably sharper. I was editing them and zoomed in quite a bit, but loss of image quality is still not something you want to see. Disappointing as other reviews had said there was no issue with this.

Another annoying thing is that if you set the cpl where you want it and then realize you want a bit of ND, moving the ND moves the cpl, so you have to readjust the cpl again. So you always kinda have to be aware to set the ND first.

I will still use this as 1) I'm overseas so it's a pain to return and 2) it still has it's uses and I can just go without for images where fine details are important.

I’ve been a fan of K&F Filters and accessories for some time now, and have come to appreciate the consistency and the quality of the brand. The majority of my lenses live their lives with K&F UV protective filters on their front element.

Like many others, as the caliber of mobile phone imagery and videography have improved to levels of near professional quality, I’ve begun to concentrate more energy into taking advantage of those attributes, not to mention the portability. Both in videography and photography, whether using a full-size camera or a high-end mobile phone, I consider both ND and CPL filters essential.

In hand, the K&F Concepts combination Variable ND2-32 and CPL filter gives the impression of quality. Between its matt black finish, the gold adjusting levers and the reflection of the multi-coatings, it’s also an impressive filter. In fact, I own a couple K&F variable ND filters in other sizes, although this is the only one that includes the CPL.

A variable ND filter works in a similar manner to a CPL, that is, there are two-rings, one that attaches it to a lens and the other that is turned to control the degree of transmission from more or less light, effectively allowing control of exposure. In this case, it’s the CPL that attaches to the front of the lens, with the ND component in front of that. In order to control each independently, the CPL has more resistance when being adjusted than does the variable ND component, which is adjusted using the gold levers on the side of the filter. That being the case, the user first adjusts the CPL to the desired position, then adjusts the variable ND to facilitate the desired exposure; it’s a system that is thoughtfully designed.

A ND filter, whether variable or not, is used to reduce the amount of light reaching a light sensitive material. In videography, it is generally used in order to follow the convention of a low ISO and a low shutter speed or a specific shutter angle. In still photography, it's used to allow for the use of a wider aperture in bright light situations or to reduce shutter speed for some desired effect. In either case, the benefit of the K&F Variable ND filter component is that the transitions between minimum and maximum light reduction are not stepped, but infinitely variable between its 2 - 5 stop range. In other words, one can set their camera to the desired settings, then rotate the light reducing transition ring to achieve the desired matching exposure.

A CPL Filter is used to reduce or eliminate certain non-specular reflections and also to saturate colors, for example a blue sky. Generally, a CPL itself requires a certain amount of exposure compensation, in my experience somewhere between 1.5 – 2.0 stops, because they also add neutral density when placed in front of a lens. Interestingly, and baffling, is that K&F has compensated for the ND effect of the CPL in their calculation of the variable ND component of the filter; when the ND is adjusted to its minimum variance, that is ND 2 (or .3), only one stop of exposure is reduced, not one stop plus the exposure reducing effect of the CPL.

Testing the filter for any reduction in image sharpness not only revealed none, but the example with the filter in front of the lens actually looks a hair sharper to my eye; each image has been enlarged to 505%.

The K&F Concept Variable ND plus CPL Filter comes from a trusted manufacturer, is high quality in fabrication, light transmission, and materials, and is essentially two filters commonly used together in one efficacious assembly. In other words, this single assembly allows for some control over distracting reflections, can enhance color saturation and allows for precise control of exposure settings, in what can otherwise be uncontrollable circumstances.

The K&F Concepts Variable ND plus CPL Filter is delivered with a hard plastic case and a nice cleaning cloth.

I have had a few K&F filters over the years...and I have found it to be hit and miss...but there are a lot of variables involved and I still go back to them.
This one is a hit.
I have included two images...involving some greens and blues...one is maximum ND and one is minimum ND...only the shutter speed was adjusted for exposure...and both images look natural and clean...good details in the pines.
I like the build quality, it has a nice heft to it.

So...why not 5 stars then? Just one niggle. I appreciate the adjustment grip on the sides...both sides...nice. But I think it needs to be dampened a bit more...just seems to slide too easily, and with the two grips protruding (you can take them off)...the filter could be moved without my even being aware.
It's a small niggle...I will live with happily...not a big deal...just not perfect...few things are.

Nice bit of kit...big thumbs up!!