This polarizer seems well made. I can't really speak to the optical quality as I am far from a professional photographer. I looked closely and didn't see any obvious optical distortions or artifacts and it looked clean through the viewfinder of my Nikon ZF with the Nikon 28-75 zoom lens attached.

The filter is quite thin, which can make it a little difficult to grip the polarizer ring in order to rotate it. However, that thinness means there should be no vignetting when shooting at wider angles. Indeed I saw no vignetting at 28mm with this filter attached. But when I stacked a UV filter with this filter there was mild vignetting. I don't have any 67mm filter threaded lenses wider than 28mm that I can test with to see at which focal length vignetting appears but based on the fact that stacking with my UV filter introduced vignetting I don't know that you could go much wider than 28mm.

I think it would be better if more of the polarizer ring was knurled to improve the grip for twisting. There are two knurled regions each of which spans about 60 degrees of the perimeter (see 2nd photo). I would prefer to see the entire perimeter knurled except for the small area where the filter specs appear.

Twisting the polarizer has more resistance than I expected, but I suppose that is good because it will keep it from losing its position once you set it. Also, it is important to remember to always turn the polarizer in the counter-clockwise direction or you might accidentally unscrew the filter from the lens while twisting it to adjust the polarizing angle.

The highlight for me was the included lens cap with the nifty lens cap keeper. I hate those cap keepers that use double side tape to attach to the lens cap. The one included with this filter is just perfect.

I wish the box the filter came in was smaller so it didn't take up so much room in my bag. You can see from photo 1 that there is quite a bit of empty space.