This neutral filter works great. I only use it outside when it's sunny, and I always require the minimum nd2 of the filter (no need to buy one that starts at nd0). At the same time, nd400 is the perfect maximum so that even parts of the sky at midday don't look overexposed. Like most variable density neutral filters, since they are just two polarizers, you can vary it 360°, but you shouldn't go over nd400 even if you can. In the indicated range you will never find any problems with vignetting or X-shading. And it's great that the quality of the (nano)polarizers allows this wide range without any problems and everything is homogeneous. In theory, the only problem with this filter (compared to 200€ polarizers like the PolarPro) is the possible slight color deviation towards a small green tint for blacks. I don't really notice it at all, so it's not a problem for me. Oh, and like any variable density neutral filter, since it has two polarizers, you can use it as a single polarizer (see video), so there's no need to buy the 2-in-1 version. By just unscrewing the filter a little you'll get a moment when reflections are avoided. Obviously, like any polarizer, it will only work for reflections at the Brewster angle (about 56° for most glasses), which uses the physical phenomenon of polarization by reflection (at a certain angle the reflected light comes out linearly polarized). And one last thing, the fact that it has the orange piece that makes it more "fancy" when rotating, that is, adjusting the nd of the filter, means that you can't use, for example, a lens hood with the filter. But it can be easily removed with a torx screwdriver (t1, t2 or t3, I don't know which).