K&F makes solid filters, and this UV filter is no different. My 24-70 has been naked for some time and I decided it was time to get it a protective UV filter as I've brought it back into my rotation of travel lenses, so I ordered a matching 77 mm filter. The K&F filter surprised me when I first unboxed it. First, the case is fantastic. It's a hard-shell smoky-transparent plastic case that is secured with 4 tabs and a short rotation to lock and unlock it. It's a large filter case because the same case accommodates 82 mm filters, but it will also accommodate smaller filters down to 43 mm. And the filters won't slide around. But how? Inside the case are two conical sections of silicone, a small one with 2 ridges and a large one with 10. The large one has numbers next to each ridge indicating the size it fits (43, 46, 49, 52, 55, 58, 62, 67, 72, 77, 82). The small one with 2 ridges is meant to hold the opposite end of the filter and stabilizes it. So as long as your filter is one of those listed sizes, it should fit in this case and is held securely in place due to the silicone ridges. Now, it's held my single-layer filters without issues, but it doesn't accommodate my variable ND filters or filters with rotating handles/extensions that jut out.

The filter itself is very well constructed. The aluminum body has two sections of thick knurling built in so it's easy to grip the filter for installing and uninstalling. The filter itself doesn't noticeably impact my image quality on my 24-70 compared to without the filter when I examine an image up to 2x in Lightroom, and I don't notice a significant color cast either. For me, the K&F UV filter is well-constructed and good to use.