The K&F Concept 52MM Multi-Coated UV Filter is a high quality product. Its build quality is on par with major filter manufacturers like Hoya and Nikon. It comes with an oversized case that I find too bulky. I like the smaller Hoya cases. Still, with a UV filter, you would probably leave the filter on the lens 100% of the time, so you don't need to carry the case. In terms of optical quality, it beats my old Nikon L37 52mm by a mile. My L37 has what looks like no coating at all and is very reflective. The K&F has a green cast to the reflection, indicating the presence of multi-coating. When the K&F looks through the two filters one after the other, it immediately shows higher contrast. Wow, what have I missed? I will be replacing my L37 with the K&F on my old 35mm lens immediately! Comparing them to my Nikon L1Bc 52mm, they look pretty similar to the L1Bc in reflection and transparency, maybe a little better at muting reflections. In other words, the K&F Multicoated UV filter is very comparable to the performance of the Nikon L1Bc without the intended red cast on the L1Bc. In summary, the K&F 52MM UV filter is an excellent filter for lens protection without significantly affecting image quality. It will replace my old L37 in a heartbeat. I'm very happy with it. Pros: - High quality build - Comparable to major brands like Hoya and Nikon - Excellent optical quality - Multi-coating reduces reflections - Higher contrast than Nikon L37 - Comparable to Nikon L1Bc without the red cast - Good lens protection Cons: - The oversized body is bulky and I prefer smaller Hoya cases