Many of my Tamron lenses for Sony E-mounts have a 67mm filter size, and I've used larger filters from my DSLR days using adapters. So testing the K&F Concept ND filter set came at just the right time. The set comes in a compact cardboard box. It contains three individually wrapped ND filters, individually wrapped dust cloths, and a well-made and practical carrying case. The filters' build quality makes a very good impression, and I'm impressed by the quality K&F offers for such a low price. My question was whether the filters' optical performance would match this positive impression. I haven't tested the ND filter graduations, but my gut feeling is that the stated ND values are achieved. I could detect minimal color shifts in the optical quality of my test images. However, these are completely negligible for the low price. In my opinion, only significantly more expensive, higher-quality filters offer better results. I doubt that this is even necessary as an amateur or hobby photographer. If you use K&F filters for videography, you can completely ignore these minimal color casts. Overall, the K&F Concept ND filter set is definitely worth recommending. At just under €40, the filters are very affordable yet still of good quality. Therefore, the filter set clearly deserves 5 stars and an unconditional recommendation.