had actually used the K&F Concept ND filters for my DJI drones and GoPro for years and was always satisfied with them. Now I have received this from K&F for testing my new GoPro. Delivery was quick thanks to Amazon. The filters fit my old GoPro 10 and also my 11s. The filters from K&F Concept too, of course. There is not much difference in price between the two sets. K&F are about 5EUR cheaper. The filters are well made and sit firmly on the camera body. Even with a lot of action and turbulent scenes, there is no need to worry. The filters remain reliably in place. The exposure time is lengthened by the ND filters and the pictures simply look much better than without them. There are some good apps that recommend certain ND filters depending on location, time of year and position of the sun/time. Lens flares in backlit shots are also largely suppressed. The lenses are easy to clean and a case is included for transport. I can only recommend. I will use these ND filters for the GoPro 11 and my son will then get the GoPro 10 with the K&F Concept filters. :) How come? Because in detail, the K&F are a little better, especially with backlighting in the sun. But only minimally.