I had the specific need for the CPL filter (circular polarizer) to take photos including bodies of water in the mountains and this filter proved to live up to expectations.
Since this is a filter for a high-end drone, I believe that those interested in such an accessory know exactly how to use it. I will therefore focus on my personal impressions of use.

First of all, it is very easy to remove it from the plastic case, but as far as the operations of adjusting the ring are concerned, I recommend using the included piece to avoid dirtying the lens. The thickness of the same ring, which slides just right without being too loose, is really very small, so care must be taken.
The assembly takes place through the tried and tested insertion and rotation system thanks to the three teeth that perfectly match the corresponding grooves placed on the drone's lens group. The operation is very simple and the assembly is absolutely firm.

As far as the results of the photos are concerned, I am certainly very satisfied. The reduction of reflections was effective and the color rendering did not suffer unwanted changes compared to using without filters. I used all three focal points of the drone and even with regard to the problem of distortions I did not find any particular anomaly.

In conclusion, a filter with excellent value for money, very light and easy to assemble. Absolutely recommended.