After using the ND filters set for my DJI O3 Air Unit and loving them, I ordered a set from K&F Concept for my DJI Osmo Action 4. The quality of the filters is excellent, they are very durable, and the included protective/organizational case is very nice and keeps them sorted and safe in my backpack.

Nice looking PL filter, and it's been a treat for outdoor filming. It's a 4 PL filter that effectively reduces glare from non-metallic surfaces. Crafted with high-grade AGC optical glass, it ensures exceptional clarity and minimal distortion.

The standout feature is its 28-layer multi-coating technology, K&F Concept have rarely disappointed when it comes to photography equipment and their filters are no exception. This filter significantly reduces reflections and glare in challenging lighting conditions. It's particularly effective on water reflective surfaces. However, it's worth noting that it can't be used underwater which kind of negates it’s use out on the lake, which is a big negative for me, but overall, it's a valuable addition to my outdoor photography/videography gear. I recommend.

I got this to test on my action camera 4

It is very nicely presented in a plastic carry box and the lens really secure inside allowing for transportation without the worry of damage and or scratching.

The filter fits my DJI Action Camera 4 perfectly and is very slim and looks great.
The threads are perfect and the materials (aircraft grade aluminium) are as good as it gets this fits perfectly without an issues. Once finished remove and put safe away in the case. Just remember can’t be used under water.

This is an amazing piece of kit and works much better than I anticipated, the reduction in reflection and glare was amazing, im tempted to buy the set of 4 made by the same company.

Happy to recommend

I was sent a returned item covered in fingerprints on the glass, and dust. Some of the dust was between the glass and the metal, and as such impossible to remove. Sent it back.

[UPDATE: K&F contacted me and sent me a replacement free of charge. The great customer service bumps up their rating from a 1 to a 4. I appreciate their effort, but sending used/bad product wasn't cool].

Great for shooting in very bright conditions , usual good quality from K&F which I use on most of my cameras.

I have both the GoPro 11 and the DJI Osmo Action 4 cameras, as well as the DJI Mini 3 Pro drone. I use ND filters for all of them and the drone ones also come from K&F Concept. I'm very happy with them.

The really cool thing here is that these are both ND and PL filters. Why? Because if you have them as separate filters, there's no way to use them together.
If you're looking to get these, you're probably aware what ND/PL filters are. But there's a small chance you may just be exploring various available accessories for your new camera. So ND filters will help in that really sunny weather, where your camera sensor gets too much light and the picture looks overexposed. It blocks an amount of light depending on which filter you use. The result is better contrast and richer colors. The PL filter further enhances it by removing unnecessary glare. Now glare can be found in more than just the surface of water. It can be a glass or metal object, snow or even…leaves. Just look at the video.
The filters are really well made. The glass looks and feels strong and solid, the threads fit perfectly and the whole thing looks really professional. The PL filter can be regulated by twisting the ring.
I like the storage box. It's hard plastic with some nice foam cuttings. The filters are easy to take out and well protected from damage.
The weather wasn't good enough when I filmed the video, but at least I had some sunshine. Summer's gone - what can you do? The difference the PL filter was making can be clearly observed though.

I've seen loads of videos where people don't utilize these filters enough. It's a quick operation to swap them (much quicker than on the drone!), so I'll have them with me everywhere. The price at £43 for 4 ND/PL filters of this quality is really good. Definitely happy to recommend.

Thank you for reading my review. I hope you found it helpful.

These K&F Concept filters are spot on.
They are really nicely made and come in a nice little protective case.
You'll know what ND filters are for if you're looking at them, but if you don't just think of them as sunglasses for your camera.
You get ND8, 12, 32 and 64 so you get equivalent f stop reduction of 3,4,5 and 6 stops.

When using the action cam in sunshine on holiday, not often in the UK :) it can help colours look cleaner and reduce glare etc.

They screw on and off the action cam really nicely.

I'm unsure as to the waterproofing side of things but I assume they'll be fine. I just put the original on when I'm in the water just so I know my warranty is covered.

Excelente calidad, se ajusta perfectamente a la action 4. Se coloca mediante rosca - no a presión - por lo que da mas confianza en actividades intensas. Funciona muy bien.

This polarising lens arrived in a shrink wrapped cardboard box. Inside, the lens is in is own plastic storage case with a custom foam insert.

It screwed onto my Osmo 4 Action perfectly. The polarising lens rotates smoothly with just enough resistance (see video).

To test this I took a couple of pictures of our garden pond. The reduction in the reflections from the water is obvious but what most impressed me was the way it removed the glare of light being reflected from the leaves of the plants to the left of the water (see pictures).

This is a good polarising lens that fits the Osmo 4 action perfectly and performs well. My only criticism is that the product is described as waterproof but can’t be used underwater, so it can’t be used in situations where the camera might get a proper soaking and I’m removing a star because of this.

excellent perfect attachment for your DJI Action 4
Good quality - fit and finish is exact as I'd have wanted
Polarizers are great for eliminating reflections and for darkening skies
this is the standard fit - no issues whatsoever
great price and quality
and a must have for any water /snow sports