The K & F Concept ND filter set is rated in ND 8, 16, 32 and 64 for DJI Mavic 3 Classic.

The filters are delivered in a small plastic storage case. It contains the 4 filters, embedded in a foam rubber mold. Thanks to the foam rubber, they remain reliably in place and are well protected against scratches.

The filters themselves consist of a metal frame and tempered optical glass.
They are included in 4 different strength classes. For most uses, the filters should be sufficient to extend the drone's shutter speed as you wish and thus create a cinematic motion blur in the image. Or simply to be able to expose the image correctly.

The filters have a very good workmanship. They fit onto the drone's lens with millimetre precision. The filter holder snaps gently into place. The filters can also be simply turned down again.
I find it very good that the filters are made of metal. In addition, one weighs just 8g, which means that the flight characteristics of the drone are not changed.

The compensation is excellent, the filter has no color cast.

Conclusion
In my opinion, the K&F Concept ND filter set is a very good product. The filters are neatly processed + the set is cleverly put together. You won't take long exposures with ND256 or higher filters out of the air anyway, so I think the ND 64 is the all-purpose weapon for very bright environments or very long shutter speeds for motion blur.
At the time of my review, the price of the filter set is around EUR 50, -- which in my opinion is an excellent price/performance ratio.
I therefore give it 5 stars and hope my review was helpful.