Even if the GoPro cameras take very good pictures with the basic equipment, in certain situations you can no longer get any further without the appropriate filters. The filter set from K&F Concept offers very good quality here. I've been a big friend of the K&F Concept filters for a long time. I've been using the filters from this manufacturer on my drone for a while now and I'm very happy with the results. The filters for the GoPro also absolutely impress me. The filters fit perfectly on the GoPro (hero 9 for me). They can be swapped out in seconds and are just as secure as the original GoPro glass. Since the filters are only slightly heavier than the original glass, there are no problems with using a gimbal. I really like the fact that this set directly combines ND and PL filters. So you have the combination of "sunglasses" and polarizing filter directly in one filter attachment. The filter is rotatable, so you can also adjust the direction of polarization. On bright summer days, or even in the snow, the filter set can be used to noticeably improve the recordings. As a rule, however, the ND8 or ND16 filter should be used in most cases. The two higher filter levels are primarily suitable for long exposures or in extreme sunshine. The optical quality of the filters is very good. There are no problems with distortion or other image disturbances. In terms of quality, there is absolutely nothing wrong with the K&F filters. Conclusion: A very good filter set at a reasonable price (currently around 70 euros). I can only recommend the filters from K&F Concept, I have never had any problems with this manufacturer. Definitely full 5 stars.