The ND filter set for the GoPro Hero 9 - Hero 11 was well packaged and delivered quickly. The four supplied ND filters should also act as polarizing filters. You can get great results with these filters. Especially on sunny days you catch more details. But the filters are also ideal for water recordings or the like, as metallic reflections are eliminated. I could also see this in my test shots. I had similar experiences with the ND filters. These are like a pair of sunglasses for the camera, the higher the value, the darker the image. When filming in 4K 30fps, the shutter speed should be 1/60 to make the footage look cinematic. However, this is impossible on sunny days, even if the ISO is 100. So it needs an ND filter to darken the image. If you want to record with 60fps, you should set the exposure time to 1/120. This requires an ND filter with a small value. So far I have only used the ND8 and sometimes the ND16 filter on very sunny days. The other filters are only suitable for special applications or for long exposures. I am also satisfied with the processing quality of the filters. They are made of aluminum and glass and are very light. The filters can also be attached and removed without any problems. They also sit very firmly on the camera. Finally, you get inexpensive ND filters with an integrated polarizing filter that help you record the video with the ideal exposure time.