I tested the filter set for the Mini 4 Pro from K&F Concept as part of the Amazon Vine program and can now describe my experience with the product without any outside influence.

The six filters are delivered in a sturdy transport box made of light but durable plastic, measuring approx. 10.3 x 10.3 x 2 cm and thus significantly oversized. Unfortunately, I can no longer fit this filter box in my drone bag and I don't understand why K&F Concept wastes so much space. The foam padding is very high and thus protects the filters, but it also makes removing them a little fiddly.

The set includes the gray filters ND 4/8/16/32/64/1000. Due to the lighting conditions, I only tested the filters ND4/8/16/32. Since I use the drone a lot for taking photos, the ND1000 is actually never used, and the light has to be very bright for the ND64. Instead of ND 1000, a polarizing filter would be much more important to me. All filters are clearly marked with a print on the frame.

Mounting them on the Mini 4 Pro is easy and takes just a few seconds. However, I noticed that the filters do not sit quite as flush as filters from other third-party manufacturers that I have already tested. Nevertheless, all filters sit absolutely firmly on the gimbal and work perfectly on the drone. I could not detect any optical impairment.