bought a 77mm D Series VND filter for my 70-200mm F2.8 lens back in March 2024. I'm not a professional photographer, so I don't use my camera very often and usually avoid shooting in high-exposure environments. I finally used the filter for the first time at a car show in June 2024 under bright sunlight and noticed some focusing issues. After some research, I found out this is a common problem with the specific lens I use. Since the return window had already passed, I decided to reach out to KF Concept directly. I explained my situation to them, and they were super understanding. They allowed me to return the filter with a restocking fee and even offered me a discount on a recommended replacement filter. I thought that was really nice of them, especially since it was my fault for not testing the filter when I first got it. The Nano-X Series VND filter they suggested works perfectly, and I couldn’t be happier with it. KF Concept’s customer service was fantastic, and they made sure I felt supported throughout the whole process. I’ll definitely keep buying their products. It’s really reassuring to know that their customer service has your back and is just as excited about their products as you are.