Filters are probably the most important thing you can buy to improve your action cam footage and this set does not disappoint.I went with the kit that came with 4 different strengths of linear neutral density filters and also came with a circular polariser and a diffusion filter. _x000b__x000b_How these filters work is that you push them over the top of the existing lens protection cover that comes with your Osmo Action 6. They have soft silicon grooves that grip the protection cover instead of a traditional filter thread. I initially I feared this would make them prone to flying off but they attach very firmly. I feel confident that they want detach accidentally. Hopefully this holds up over time.They come in a a nice plastic case with protective foam inside. I would have liked to see this case be a little smaller personally. It is big enough that it becomes annoying to try and fit it into a bag. Still, I appreciate the fact that they do have a case and they also give you a small little microfibre cloth to clean the filters with. I've added it to my large pile of other microfibre cloths I've collected.The filters themselves are effective. The circular polariser I found very useful for cutting out reflective surfaces, something that is often helpful on an action cam when attaching to windscreens or reflective paint work. It really improves an image by controlling scattered light leading to improved colours in things like the sky. I also really like the diffusion filter for cutting down on the digital sharpness that is present in most action camera footage, with the Action 6 being no exception. It gives a nice little halation to the highlights without being too overbearing. The ND filters are obviously useful for filming in direct sunlight or even on bright but cloudy days by darkening the image. More control over your exposure can let you bring back in some of the natural motion blur that is lost when the camera ratchets the shutter speed down to get correct exposure.My biggest issue is that I want to use a combination of these filters most of the time. But the snap on design means that I can't. This isn't really a fault of the filters necessarily, but they are all just so helpful in different ways that I want to combine them like I do on my main mirrorless camera. Stacking filters on such a wide angle lens would result in vignetting of course so it's understandable that they haven't been designed to allow this.One solution to this is to buy a set of filters that replaces the screw on protection filter and then using a filter from this set over the top of that filter. K&F do make a set that replaces the protection cover so I would advise buying that one to ensure that it will be the right size for compatibility. It's likely that other brands do work though.I think the smart thing to do would be to use a screw on ND from another set and then use either the polariser or black mist from this set in combination with it. If you have a think about what combination you are likely to use, then you can buy only the filters you will need from this set. It's nice of K&F to give us so many combinations of filters to buy on this listing.I think any of the filter combination options here provide good value for money. Filters really expand your capability and these ones are made of nice materials, feel solid and do the job well.