Another win from the folks at K&F! This circular polarizer is excellent and has thankfully found a place in my camera bag! Sure, I have other polarizers from other manufacturers at 1.5 to 3 times the price and at the end of the day they all do the same thing. It all comes down to the materials, fit and quality of the elements/films/coatings. For the K&F, this ticks all the boxes and is certainly price competitive. The polarizer screwed directly onto my powerful Canon EF 27-70 2.8 L lens as well as my EF 16-36 2.8L without any of the snagging, pulling or dragging that cheap filters tend to have. Once mounted, you can rotate the filter's aperture to adjust the polarization to your needs. I haven't done an extensive study on this to see if there is a color cast or defraction, but I haven't noticed any anomalies when using the filter. And no, it is not permanently attached to my lens as I probably don't need polarization. The filter comes with one of the K&F lens cleaners as well as a spare lens cap (K&F brand) which is a nice spare part. Also comes with a small lanyard. The filter and lens cap come in a reusable, padded plastic storage case for safe keeping. I've included a few photos of the contents of the box.