Always trusted K&F Concept for filters, and these Snap on ones are quality! The optical glass is excellent, very clear, and they do a great job of controlling light without wrecking image quality.These are snap on filters rather than screw on, which for me makes them very easy to take on and off, especially when out riding. I can confirm they fit the DJI Action 6 perfectly. I also tested them on an Action 5 and they are too big, so they are not interchangeable across models.I use an action cam on my motorcycle, and vibration is part of life. On older snap on filters I have had the odd occasion where vibration caused one to come loose, and these feel like a similar fit. It has not happened often, but it is something worth being aware of if you ride regularly on rough roads.In use, they perform brilliantly. I often ride in bright conditions where footage can end up overexposed, and these filters sort that out straight away. ND8 or ND16 covers most UK weather perfectly. ND32 and ND64 are less commonly used for me.They are not cheap, but the build quality and optical performance match the price. For me, they feel like good value for money if you care about image quality and want filters you can rely on.