have probably 20 reviews on different filters from this company. I don't think I've ever had a reason to write a bad review either. I don't have any calls here either. These clearly use the same high quality optical material. It's just a different form factor, this case for a GoPro. The filters are of the excellent quality I have come to expect from K&F Concept, so they didn't make the materials cheap just because the filters were a different shape and smaller. I bought one of those kids that give you about 100 things for your action camera and it comes with some filters. You can just hold them up to a light and see the difference in quality between these and the ones that came with this kit. They're so much better. I find that for an action camera you need a neutral density filter even more when shooting video in very bright leaf-lit areas. It lets you open your aperture if you want a shower in depth of field, and lower the frame rate if you need that. These are different than a polarizing filter if you're just worried about glare, though. If your problem isn't glare, but simply too much light all around, then opt for a neutral density filter. Luckily, this kit includes three stops of neutral density apertures starting at 1/8 and also gives you a circular polarizing filter to eliminate that glare. The filters fit the GoPro perfectly so I don't have to worry about losing one and great optical quality. I would say such a kit is absolutely essential if you own an action camera. I'm not sure if the value for money for this set can be beat anywhere else.