I've used these filters with both my GoPro Hero7 and Hero6 and they work great, fit tight, and provide a clear image. The polarizer is fantastic. I'm not sure why the refer to it as CPL, as the design is clearly not an adjustable circular polarizer, but for reducing glare without producing too dark an image, it works fantastic.
The magenta worked great on my Hero7 when snorkeling with free dives. I used the red for some sunset pictures and it gave beautiful effect. I haven't used the yellow for any filming, but tried it out and it fits and works as expected.
The build of these lenses are high quality and I'll be getting the ND filters from this company as well based on my experience with these. If your thinking of getting the snap on filters or the more expensive filters from other companies, save your money and purchase from QKOO instead. High quality and half the price of the more expensive brands. You won't be disappointed.