Set of K&F Concept filters designed specifically for the Insta360 GO Ultra, really useful for those who want to make the most of this small action cam, especially when shooting in bright light or want to give a more professional touch to their videos. The kit includes four filters: an ND8, an ND16, an ND32 and a CPL polarizer, practically everything you need to manage the most common situations you may encounter while shooting. The filters have a well-finished metal frame and the lenses seem to be of good workmanship with a multilayer treatment that helps reduce reflections and protects against dust and fingerprints, although obviously you should always handle them with a little attention because the small size makes them delicate. The installation on the GO Ultra is very simple, the filters are screwed directly onto the camera lens safely without wobbling, and this is essential considering that we are talking about an action camera that is often used on the move or attached to moving surfaces, once mounted they do not interfere with the rest of the camera and do not create vignetting in the footage, which frankly worried me a bit given the ultra wide angle nature of this small camera. ND filters are particularly useful when shooting in broad daylight or in very bright environments, they allow you to reduce the amount of light that enters the lens without altering the colors and this gives you the opportunity to use longer exposure times to obtain that natural motion blur that makes videos much more fluid and cinematic. The ND8 is good for slightly cloudy days or for the late afternoon, the ND16 is perfect for full sun while the ND32 I use it mainly when there is really a lot of light such as in the mountains on the snow or at the sea with the reflections of the water. The CPL polarizing filter, on the other hand, is what I use the most when I want to eliminate reflections from surfaces such as glass or water, or to make the sky more saturated and dramatic in outdoor shooting, it works well and by rotating it you can clearly see the effect it has on the scene so it's easy to find the right angle before starting to record. Overall, however, I am really satisfied with this set, the quality-price ratio seems honest to me considering that these are four filters of decent optical quality and that allow you to significantly expand the creative possibilities of the GO Ultra, if you often use this outdoor action camera or want to give a more professional look to your videos, I definitely recommend considering them.