This set of four filters from K&F Concept are the first not mounting accessories I have for my Insta350 Go Ultra. They take advantage of the Go Ultra’s screw on and off lens filter system. I went for the 4 pack with CPL, and 3 ND filters in 8,16 and 32. The filters are all significantly larger than the one that comes with the Go Ultra (this does mean the original lens cover rattles around in the filter box.) The biggest surprise was the CPL filter had a rotating element letting you dial in the polarising in; and it works well. The ND filters are a good range for an action camera, especially if you aren’t using them in the gloom of October. They all have a good even density grey across the filters, and they didn’t introduce a significant colour tint in my video footage.Thanks to the screw on and off design the filters are easy to use; the high-quality glass in the filters helps them a great solution for the Go Ultra. The CPL makes reducing haze and reflections in footage easy. The ND filters are great in bright light and make a handy pocket camera give better footage in more lighting conditions.