received this product as a free trial as part of the Vine program. Thanks very much. The price for the 77 mm variant is in a demanding range at €180; the expectations are corresponding. I compare the filter side by side with my Käsemann B+W KSM HTC-POL MRC nano XS-PRO DIGITAL, which is about 25% cheaper depending on the source. The K&F circular polarizing filter comes in a high-quality cardboard slipcase packaging. The actual case is just as high quality. The question is whether such a chic case is also ideal for transport - or whether the classic plastic filter box does not offer better protection against mechanical damage or moisture. I mean yes. Visually, I think the K&F filter is excellent, and that's the main thing. I can't tell the result from my Käsemann B+W filter. Both filters swallow a little more than 1 f-stop of light. The effect is indistinguishable. I don't notice any optical impairments or color shifts. See photos. In my sample photos, I worked with a constant white balance. The filter can be easily screwed in. It is approx. 5 mm thick without the filter thread, my Käsemann B+W filter is only approx. 4 mm. Now my point of criticism, which leads to the deduction of a star. The filter is relatively stiff when new, in contrast to my Käsemann B+W filter. By turning it back and forth several times I got it smoother. But the circulation isn't quite even, there are places that run better and places that offer a little more resistance. No problem at all, the filter can be used without any problems, but as I said, we are talking about a high-priced product and I have the direct comparison. Four stars.