Optically, nothing wrong, the filter looks very good. It is also exceptionally fine for a circular polarizer (no thicker than a protective filter) to avoid vignetting. However, it is not always necessary to take such a fine filter if your goal is not "limit" on that side. The contour of the screw-in metal ring is "notched" on a large part of its perimeter, which greatly facilitates the screwing / unscrewing (practical and fairly standard for this type of filter given the screwing / unscrewing regular).
A small arrow on the rotating ring can easily spot your favorite direction and serves as a benchmark to adjust quickly the filter when you alternate horizontal and vertical framing.
Small flat, the filter is so thin that there is not enough grip for the original lens cap (Nikon, in my case) will hold as reliably as usual. Things to consider before you buy, this can be a problem depending on your use. Nothing dramatic in my case, but it cost him the 5th star.
